Harmonic pin ring gearing

ABSTRACT

A harmonic ring gear system can include at least one inner gear with external toothing, the at least one inner gear defining an axis of rotation; at least one outer gear with internal toothing arranged concentrically to the at least one inner gear about the axis of rotation, the internal toothing spaced apart from the external toothing; a pin ring positioned between the at least one inner gear and the at least one outer gear, the pin ring comprising a multiplicity of pins; and a rotary transmitter configured to lift a portion of the pins of the multiplicity of pins off the external toothing and press the portion of the pins into the internal toothing.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/454,249, filed Jun. 27, 2019, which is a continuation of U.S.application Ser. No. 14/778,404, filed May 17, 2016, which issued intoU.S. Pat. No. 10,371,240 on Aug. 6, 2019, which is a 371 of PCTApplication No. IB2014/059999, filed Mar. 20, 2014, which claims thebenefit of PCT Application No. IB2013/052217, filed Mar. 20, 2013, eachof which is hereby specifically incorporated by reference herein in itsentirety.

The invention describes inter alia a novel pin ring gear system, aninner ring and an outer ring for such a gear system and a tooth profilesuitable for this gear system. This novel pin ring gear system isreferred to below as a “harmonic pin ring drive”.

US 2009/0139358 discloses a method for setting a tooth profile for aflat harmonic drive or a strain wave gear system having a flexibleinternally toothed gear and a rigid externally toothed gear. Itspecifies a tooth shape for the internally toothed gear on the basis ofwhich the profile of the externally toothed gear is then determined.

This description discloses a harmonic pin ring gear system with an inputshaft and an output shaft, wherein the input shaft can take the form ofa rotor shaft and the output shaft can correspond to a region of aninner gear with a driven shaft or hollow driven shaft.

The harmonic pin ring gear system comprises two outer gears, each withinternal toothing. The outer gears can, in particular, be spaced apartin axial direction, wherein a spacer such as, for example, a sleeve canbe arranged between the outer gears.

A single inner gear with external toothing is arranged concentrically toa first outer gear and in axial direction inside this first outer gear.Here a single inner gear with external toothing also comprises amulti-part inner gear with multi-part toothing, as long as thecomponents of the inner gear form one assembly unit, while the secondouter gear has no corresponding or radially opposite inner gear withcorresponding external toothing. This arrangement is also referred to asa 2.5-row pin ring gear system while a gear system with twocorresponding internal and external toothed elements and one transmitteris referred to as a 3-row pin ring gear system.

In other words, the pins projecting laterally beyond the drive means onone of the two axial sides are supported in radial direction outwardsonly in the first internal toothing, while the pins on the other axialside are supported in radial direction both inwards in the externaltoothing of the single inner gear and outwards in the internal toothingof the corresponding outer gear.

A drive means comprising a pin ring or pin-retaining ring formed as onepart in circumferential direction and a multiplicity of pins thatprotrude laterally from the pin-retaining ring in axial directionextends between the two outer gears and the inner gear. In theapplication the terms pin ring and pin-retaining ring are occasionallyused synonymously, it being clear from the context which is meant. Inits narrowest sense, a pin ring is formed of a pin-retaining ringcontaining a multiplicity of pins. However, for the sake of brevity, apin-retaining ring without pins is often also referred to as a pin ring.

Furthermore, a rotary transmitter is provided for lifting the drivemeans off the external toothing of the inner gear and pressing the drivemeans into the internal toothing of the outer gears.

In particular, the rotary transmitter can take the form of a cam diskwith an oval or other similar shape on which a thin-section ball bearingis arranged. Alternatively, a wire rod ball bearing or a flexible ballbearing with no outer ring can be fitted. A further form of transmittertakes the form of two circular rollers axially offset in relation to oneanother and mounted such that they can rotate about their axes.

According to one of the embodiments, in a first axial region of the gearsystem a radial force flow runs in a straight direction from thetransmitter via at least one pin to the internal toothing of the outergear. In a second axial region of the gear system a radial force flowruns in a straight direction from at least one pin to the externaltoothing of the inner gear.

In particular, the outer ring, the pin ring and the inner ring can bearranged such that a radial force flow runs in a straight direction fromthe internal toothing of the outer ring via at least one pin to theexternal toothing of the inner gear.

According to one embodiment the pin-retaining ring is located in theaxial direction of the gear system on an inner side of an outer geardesigned as one or more part or parts. According to another embodimentthe pin-retaining ring is located in axial direction between a first anda second outer gear. According to a further embodiment the pin-retainingring is arranged in axial direction centrally in an outer gear designedas one or more parts.

According to a first configuration of the transmitter the transmittercan be formed such that the drive means abuts the entire circumferenceof the transmitter. This is the case with an oval cam disk, for example,but not with two axially offset rollers. In this case, the transmittercomprises an oval-shaped cam disk and a flexible thin-section rollerbearing, wherein the flexible thin-section roller bearing lies on theoval cam disk and the pins lie on an outer ring of the flexiblethin-section roller bearing.

According to a further configuration of the transmitter the drive meansabuts the circumference of the transmitter except in a first regionabout a first angular position and in a second region about a secondangular position, wherein the first angular position is offset by 180degrees in relation to the second angular position. This is the casewhere there are two axially offset rollers and is also referred to as adouble eccentric cam. Here a first eccentric cam has a first axis ofrotation and a second eccentric cam has a second axis of rotation, thetwo being offset in relation to one another. Here the first angularposition and the second angular position are each offset by 45 degreesin relation to a semi-major axis that connects the first axis ofrotation and the second axis of rotation.

In particular, the transmitter can be connected to the input shaft, forexample by being pressed onto the input shaft. The output shaft can beconnected to the inner gear or one of the two outer gears. If the outergears are connected to a motor housing, the output shaft is thenconnected to the inner gear.

According to a further embodiment the transmitter is connected to theoutput shaft and the input shaft is connected to the inner gear or theouter gear.

The pin ring or pin-retaining ring can in particular be constructed suchthat the pin-retaining ring comprises radially inwardly open channelsarranged in axial direction to receive the pins that are arranged on aninside of the pin-retaining ring.

Furthermore, the harmonic pin ring gear system can comprise a second pinring arranged in radial direction in relation to the inner ring thatfulfils the function of a support ring. Here an end region of the pinsis arranged between the second pin ring and the inner ring.

Furthermore, the harmonic pin ring gear system can comprise a middle pinring, wherein a middle region of the pin abuts the middle pin ring andthe outer gear has a channel in which the middle pin ring runs.

The inner gear can also be constructed in several parts with the innergear being split in axial direction and having an inner gear holderfixed to the inner gear. The inner gear holder is supported on an innergear roller bearing that is in turn supported radially inwards on a gearhousing, wherein the inner gear and the inner gear holder encompass anouter ring of the inner gear roller bearing.

The output shaft can in particular be designed as a hollow driven shaftand have a freewheel, wherein the freewheel is arranged between thehollow driven shaft and an inner region of the inner gear.

Moreover, according to one of the preceding claims, the harmonic pinring gear system can comprise a crankshaft and a crankshaft freewheel inparticular to induce a pedal force. The crankshaft is arrangedconcentrically in relation to the hollow driven shaft inside the hollowdriven shaft, wherein the crankshaft freewheel is arranged between thecrankshaft and the hollow driven shaft.

To provide improved lateral support for the pins, the harmonic pin ringgear system can comprise a first thrust washer and a second thrustwasher, wherein the first thrust washer is arranged adjacent to a firstaxial lateral face or end face of the pins and the second thrust washeris arranged adjacent to an opposite second axial lateral face or endface of the pins.

Improved adjustment of the harmonic pin ring gear system to achieve goodload compensation of the pin ring, in particular in a gear system withtwo outer gears, can be achieved by the outer gears being held in theirpositions relative to the central axis of the gear system by africtional connection only and having clear and intentional radial playrelative to this position when they are loose, i.e. before fixing screwsare tightened to press the outer gears against the gear housing.

According to a further embodiment the drive shaft for the transmitter,which can in particular take the form of a rotor shaft, is mounted onone side in the inner gear which is in turn mounted in the housing or ahousing cover of the housing. A press fit between a mounting of theinner gear and a mounting of the drive shaft for transmitters in theinner gear results in less displacement of the external toothing of theinner gear. The press fit also enables the use of a freewheel with noaxial guide, for example a ball bearing-mounted freewheel between theinner gear and a driven shaft. The driven shaft can in particular bemounted radially inside the inner gear.

Furthermore, this description discloses a harmonic pin ring drivecomprising a gear unit with one of the harmonic pin ring gear systemsdescribed above. The harmonic pin ring drive also comprises a motorunit, wherein a rotor shaft of a motor of the motor unit is connectedmechanically to the cam disk of the gear unit, for example by pressingthe cam disk onto the rotor shaft. In particular the motor can bedesigned as an internal rotor motor in which the circumference of astator can abut a housing.

According to a further embodiment a driven shaft is provided that isconnected to the inner gear via a freewheel. The driven shaft is mountedon two bearings, wherein the motor is provided between the two bearingsof the drive shaft. In particular, both a motor unit with stator androtor and a gear unit with the outer gears, the inner gear and thetransmitter can be provided between the two bearings. This results in anincreased supporting width and lower transmitter displacement, therebyachieving greater pin durability.

According to a further embodiment the driven shaft is designed in twoparts. Here a support shaft is fixed to the driven shaft, for example byplacing it on a shoulder of the driven shaft or flanging it to thedriven shaft. This makes it possible to increase the supporting width ofthe mounting of the driven shaft. The support shaft can be a thin sleeveif the output torque runs more through the driven shaft and less throughthe support shaft.

For example, a motor freewheel can be arranged between the output shaftor a hollow shaft region of the inner gear and the driven shaft suchthat the torque is generated at a driven side and components that usethe torque can also be affixed on the driven side while the supportshaft is affixed to an opposite drive side.

According to a further embodiment a pedal bearing shaft is arranged inthe driven shaft, wherein one or more freewheels can be arranged betweenthe pedal bearing shaft and the driven shaft.

A torque sensor is arranged in the region between the driven shaft andthe pedal bearing shaft, wherein the driven shaft is designed such thatthe torque sensor is shielded from electromagnetic radiation of thestator. In particular, the driven shaft can cover a large part of theaxial length of a coil body of the torque sensor. The driven shaft thusforms something like a Faraday cage, wherein a rotor shaft in which thedriven shaft is arranged, provides additional shielding against thestator as required.

This applies in particular if an internal rotor motor is used in whichthe stator—and also the rotor—are arranged radially outside the drivenshaft.

Furthermore this description also discloses a motor vehicle with aharmonic pin ring drive as described above, wherein a drive gear of themotor vehicle is connected to the output shaft of the harmonic pin ringdrive. The motor vehicle can, in particular, be an electric two-wheeleror an electric three- or four-wheeler such as, for example, anelectrically driven auto-rickshaw.

In a further aspect this description discloses a pin ring arrangementwith a multiplicity of pins, a pin ring to hold the pins and atransmitter to exert a radially outward force on the pins, wherein thetransmitter is arranged inside the pin ring and the pins lie at leastpredominantly on an outer circumference of the transmitter.

According to a first embodiment the transmitter comprises a an eccentriccam arranged eccentrically in relation to an axis of rotation of thetransmitter. According to a further embodiment of the pin ringarrangement the transmitter comprises a second eccentric cam arrangedeccentrically in relation to an axis of rotation of the transmitter.According to a further embodiment the transmitter comprises an oval camdisk and a thin-section ball bearing that lies on the oval cam disk,wherein the pins lie on an outer ring of the thin-section ball bearing.

A further aspect of the application describes a harmonic pin ring gearsystem with an input shaft and an output shaft. The harmonic pin ringgear system comprises an outer gear with internal toothing and an innergear with external toothing, wherein the inner gear is arrangedconcentrically to the outer gear and at least partially inside the outergear in axial direction.

A drive means extends between the outer gear and the inner gear. Thedrive means comprises a pin ring formed as one part in circumferentialdirection and a multiplicity of pins that protrude laterally in axialdirection from the pin ring. Due to the design of the pin ring as onepart in circumferential direction, instead of being made up ofindividual members connected together by joints, as disclosed in U.S.Pat. No. 2,210,240, for example, a construction as one part incircumferential direction according to this description can be quieterrunning and sustain less wear. The pin ring according to thisdescription can, however, be constructed in several parts in radialdirection. For example, it can be constructed out of different layersconnected together as disclosed in WO 2012/046216.

Moreover, the gear system comprises a rotary transmitter for lifting thepins of the drive means off the external toothing of the inner gear andpressing the drive means into the internal toothing of the outer gear.Here in a first axial region a radial force flow runs in a straightdirection from the transmitter via at least one pin to the internaltoothing of the outer gear and in a second axial region a radial forceflow runs in a straight direction from at least one pin to the externaltoothing of the inner gear. As explained below in relation to FIG. 15,this prevents or reduces any tilting or bending torque on the pins.

A first radial force flow according to this description can, forexample, be realised by locating a radially contiguous region of thetransmitter, or a radially contiguous region of the transmitter and thepin ring that is in contact with the pins, at least partially inside theouter gear in axial direction. A first radial force flow according tothis description can, for example, be realised by locating a contiguousradial region of the inner gear that is in contact with the pins atleast partially inside the outer gear in axial direction.

According to this description a radial force flow can, in particular,run in a straight direction from the internal toothing of the outer ringvia at least one pin to the external toothing of the inner gear. Thus aforce acting against the force on the inner gear can be absorbed by theouter gear in radial direction. In this way the bending torque on thepins can also be reduced.

The pin ring can be located on an outer side of the outer gear in axialdirection, for example to provide sufficient space for the pin ring.

In the case of a deformable transmitter, in particular, that has an ovalcam disk, for example, the drive means can abut the entire outercircumference of the transmitter, thereby achieving effective forcetransmission.

In one configuration this is achieved by the transmitter having anoval-shaped cam disk and a flexible thin-section roller bearing, whereinthe flexible thin-section roller bearing lies on the oval cam disk andthe pins lie on an outer ring of the flexible thin-section rollerbearing.

In a transmitter configuration comprising an eccentric cam arrangementit is possible to configure the eccentric cam in such a way that atleast most of the drive means abuts an outer circumference of thetransmitter. This is particularly true of the double eccentric cam shownin FIGS. 7 and 8. Here there are only two regions in which the drivemeans does not abut the outer circumference of the transmitter. Thesetwo regions extend in the region of two angular positions that areoffset by 45 degrees in relation to a semi-major axis of the doubleeccentric cam connecting the two axes of rotation of the two eccentriccams. This is particularly clear from FIG. 8.

If both eccentric cams in the double eccentric cam comprise a circulardisk, it is advantageous for these two circular disks to be made aslarge as possible to achieve the largest possible drive means supportregion. To achieve this it is in turn advantageous for the two eccentriccams of the double eccentric cam to be arranged one behind the other inaxial direction as shown in FIGS. 7 and 8.

In geometrical terms such an arrangement, as seen in the case of thedouble eccentric cam, for example, can be characterised by the fact thatthe drive means abuts the circumference of the transmitter except in afirst region extending about a first angular position and a secondregion extending about a second angular position, wherein the firstangular position is offset by 180 degrees in relation to the secondangular position.

In particular, the harmonic pin ring gear system can comprise a doubleeccentric cam with a first eccentric cam having a first axis of rotationand a second eccentric cam having a second axis of rotation. Here thefirst angular position and the second angular position are offset by 45degrees in relation to a semi-major axis connecting the first axis ofrotation and the second axis of rotation.

According to a first configuration that is particularly suitable forreducing gears, the transmitter is connected to the input shaft and theoutput shaft is connected to the inner gear or the outer gear. Here amechanism can also be provided for switching the connection to the inneror outer gear, for example for a change of direction for a reverse gear.

According to a second configuration the transmitter is connected to theoutput shaft and the input shaft is connected to the inner gear or theouter gear.

According to a first configuration of the transmitter, the transmittercomprises an oval-shaped cam disk and a flexible thin-section rollerbearing, wherein the flexible thin-section roller bearing lies on theoval cam disk and the pins lie on an outer ring of the flexiblethin-section roller bearing.

According to a further configuration of the transmitter, the transmittercomprises at least one eccentric cam disk and the pins lie on an outercircumference of the transmitter.

To receive the pins and to guarantee a distance between the pins incircumferential direction, the pin ring can comprise channels arrangedin axial direction to receive the pins that are arranged on an inside ofthe pin ring.

To improve stability, the harmonic pin ring gear system can have asecond pin ring arranged at least partially opposite the inner ring inradial direction, wherein an end region of the pins is arranged betweenthe second pin ring and the inner ring and the outer gear is arrangedbetween the first pin ring and the second pin ring in axial direction.

Furthermore, the harmonic pin ring gear system can also have a middlepin ring, wherein a middle region of the pins abuts the middle pin ringand the outer gear has a channel in which the middle pin ring runs.

To improve support for the inner gear, the inner gear can comprise aninner gear holder that is fixed, in particular screwed, to the innergear, wherein an inner gear roller bearing supported radially inwards ona gear housing is provided and the inner gear and the inner gear holderencompass an outer ring of the inner gear roller bearing.

In particular, the output shaft can be designed as a hollow driven shaftand the gear system can have a freewheel arranged between the hollowdriven shaft and an inner region of the inner gear.

Furthermore, in a design for an electrically driven bicycle, forexample, the harmonic pin ring gear system can comprise a crankshaft anda crankshaft freewheel, wherein the crankshaft is arrangedconcentrically to the hollow driven shaft inside the hollow driven shaftand the crankshaft freewheel is arranged between the crankshaft and thehollow driven shaft.

To improve the running of the pins, the harmonic pin ring gear systemcan comprise a first thrust washer and a second thrust washer, whereinthe first thrust washer is arranged adjacent to a first axial lateralface of the pins and the second thrust washer is arranged adjacent to anopposite second axial lateral face of the pins.

Moreover, this description discloses a harmonic pin ring drivecomprising a gear unit, one of the aforementioned harmonic pin ring gearsystems and a motor unit, wherein a rotor shaft of a motor of the motorunit is connected mechanically to the cam disk of the gear unit.

In particular, the motor can be designed as an internal rotor motor.

Furthermore, this description discloses a 2-, 3- or multi-wheeled motorvehicle with the harmonic pin ring drive, wherein a drive gear of themotor vehicle is connected to the output shaft of the harmonic pin ringdrive.

In a further aspect this description discloses a pin ring arrangementwith a multiplicity of pins, a pin ring for holding the pins and atransmitter for exerting a radially outward force on the pins, whereinthe transmitter is arranged inside the pin ring and the pins lie atleast predominantly on an outer circumference of the transmitter.

In a first configuration the transmitter can have an eccentric cam thatis arranged eccentrically to an axis of rotation of the transmitter.Here it is advantageous for the chosen eccentric cam to be as large aspossible in the sense that a radius of the eccentric cam is onlyslightly different to a radius of the inner gear.

To further increase the seize of a support region of the pin on thetransmitter the pin ring arrangement can comprise a second eccentric camthat is arranged eccentrically to an axis of rotation of the transmitterand is also chosen to be as large as possible.

In a second configuration, the transmitter can comprise an oval cam diskand a thin-section ball bearing that lies on the oval cam disk, whereinthe pins lie on an outer ring of the thin-section ball bearing. Here theoval cam disk can, in particular, be dimensioned such that a semi-majoraxis and a semi-minor axis differ only slightly from a radius of theinner gear.

This description also discloses a harmonic pin ring gear systemcomprising at least one inner ring with external toothing and at leastone outer ring with internal toothing and a pin ring that has pins witha circular cross section and a rotor with a transmitter for drawing thepins of the pin ring into the teeth of the outer ring and into the teethof the inner ring. The inner ring, the rotor and the outer ring arearranged concentrically to one another and the transmitter is arrangedinside the pin ring.

The transmitter and the pin ring are arranged between the inner ring andthe outer ring, wherein the transmitter deforms the pin ring in such amanner that the outer ring and the inner ring rotate relative to oneanother, wherein the pins of the pin ring are pressed alternately intothe teeth of the inner ring and the teeth of the outer ring. The shapeof the teeth of the outer ring and the shape of the teeth of the innerring are essentially determined by the envelope of the moving pins,wherein each of the pins meshes with the internal toothing of the outergear or the external toothing of the inner gear.

Moreover, the harmonic pin ring gear system can comprise a 3-rowstructure with a first gear wheel pair comprising an inner ring and anouter ring and a second gear wheel pair comprising an inner ring and anouter ring, wherein the first and second gear wheel pairs are arrangedin different first and second planes and a transmitter holder comprisinga transmitter in a third plane is arranged between the plane of thefirst gear wheel pair and the plane of the second gear wheel pair. Herethe transmitter holder can, in particular, be a rotor and thetransmitter can, in particular, be an elliptically shaped rotor flange

This harmonic pin ring gear system is particularly suited to thetransmission of large torques as a result of various characteristicsincluding the size of the pins, the tooth shape and the distance betweenthe inner and outer gears.

The distance between the inner and outer gears and the pin size, inparticular, are dimensioned such that the apex of a pin centre point ofa pin as the pin moves from one tooth base into an adjacent tooth baseof the toothing of the inner or outer ring lies essentially on a pitchcircle of the opposite toothing. This means that the pin re-engages inthe tooth base of the opposite teething when the pin is located on anapex of the pin trajectory between the two tooth bases of one set oftoothing.

To receive the pins, which have a circular cross section, the crosssection of the tooth bases can be shaped like a sector of a circle and,in particular, be semi-circular. According to one embodiment the toothflanks run into the tooth base perpendicular to the pitch circle of thetoothing. The steep tooth flanks provide good lateral hold for torquetransmission. In addition, with a semi-circular tooth base there istherefore no buckling.

In particular, the gear system can be formed such that the pintrajectory of a pin centre point of a pin as the pin moves from onetooth base into an adjacent tooth base is determined by a section of anellipse, in particular a half ellipse, wherein the section of an ellipseruns from a semi-minor axis to an opposite semi-minor axis of theellipse. This path shape results in the tooth shape of toothingdetermined by the envelope of the pins as described above.

In a further embodiment the pin trajectory of a pin centre point of apin as the pin moves from one tooth base into an adjacent tooth base isdetermined by a section of a sine-overlaid circular shape, in particularby half a sine-overlaid circular shape running from a semi-minor axis toan opposite semi-axis of the sine-overlaid circular shape.

In a further embodiment the pin trajectory of a pin centre point of apin as the pin moves from one tooth base into an adjacent tooth base isdetermined essentially by a shape of the transmitter compressed along anangular coordinate, wherein the compression factor can be, inparticular, Z/2, where Z is the number of teeth. Here the angularcoordinate is expressed relative to a centre point of thetransmitter/rotor in relation to a polar coordinate representation.

Moreover, the root circle of the teeth of the inner gear can essentiallybe positioned twice the circumference of the pins away from the rootcircle of the teeth of the outer gear, thereby guaranteeing good pinengagement in the toothing.

Moreover, this application discloses a inner ring with external toothingsuitable for a harmonic pin ring gear system that has the followingcharacteristics. The gear system comprises a pin ring with pins thathave a circular cross section and rotor with a transmitter for drawingthe pins of the pin ring into the teeth of the inner ring, wherein theinner ring and the rotor are arranged concentrically to one another. Thetransmitter is arranged inside the pin ring, wherein the transmitterdeforms the pin ring such that the inner ring rotates relative to anouter ring arranged concentrically to the inner ring.

The inner ring comprises tooth bases with a profile in the form of asegment of a circle that are arranged at regular distances and teethwith a symmetrical profile that are arranged between the tooth bases,wherein the shape of the teeth is determined essentially by the envelopeof the moving pins. Here the distance between the surface of the toothand the envelope should not be below a predetermined distance and thetooth shape therefore essentially follows the envelope.

In particular, the profile of the tooth bases of the inner ring can besemi-circular in shape and the tooth flanks can run into the tooth baseperpendicular to the pitch circle of the toothing.

Similarly, this application discloses an outer ring with externaltoothing suitable for a harmonic pin ring gear system that has thefollowing characteristics. The gear system comprises a pin ring withpins that have a circular cross section and a rotor with a transmitterfor drawing the pins of the pin ring into the teeth of the inner ring.The outer ring and the rotor are arranged concentrically to one anotherand the transmitter is arranged inside the pin ring, wherein thetransmitter deforms the pin ring such that the outer ring rotatesrelative to an inner ring arranged concentrically to the outer ring.

The outer ring comprises tooth bases with a profile in the form of asegment of a circle that are arranged at regular distances and teethwith a symmetrical profile that are arranged between the tooth bases,wherein the shape of the teeth is essentially determined by the envelopeof the moving pins.

In particular, the profile of the tooth bases can be semi-circular inshape and the tooth flanks can run into the tooth base perpendicular tothe pitch circle of the toothing.

According to another one of the embodiments, a harmonic pin ring gearsystem can comprise an input shaft and an output shaft, wherein saidharmonic pin ring gear system has the following features: two outergears, each with internal toothing, a single inner gear with externaltoothing arranged concentrically to a first outer gear and inside saidfirst outer gear in axial direction, and a drive means extending betweenthe two outer gears and the inner gear comprising a pin ring formed asone part in circumferential direction and a multiplicity of pins thatprotrude laterally in axial direction from the pin ring, a rotarytransmitter for lifting the drive means off the external toothing of theinner gear and pressing the drive means into the internal toothing ofthe outer gear, wherein the input shaft is mounted on one side in theinner gear, the inner gear is mounted in an inner gear ball bearing, andthe inner gear ball bearing is mounted in a housing cover.

The Harmonic Pin Ring Drive (HPRD) according to this application is aspecial gear system of rotationally symmetrical constructioncharacterised in particular by the following features:

-   -   very high power density requiring only a small installation        space    -   rigidity    -   very little play    -   very large bandwidth in relation to reduction and transmission        ratios    -   the possibility of a hollow shaft design.

These gear systems can produce both single- and multi-step speed changesand can be used as differential gears. Moreover, changes in direction ofrotation and shifting are also possible.

The object of the application is explained in further detail below withreference to the following figures.

FIG. 1 shows an exploded view of an HPRD,

FIG. 2 shows a view of the gear system in FIG. 1,

FIG. 3 shows a cross section through the gear system in

FIG. 1,

FIG. 4 shows a side view of a pin ring and an enlargement of a sectionthereof,

FIG. 5 shows a pin raceway of an HPRD,

FIG. 6 shows an enlarged section of FIG. 5,

FIG. 7 shows a cross section through an HPRD with deflection rollers,

FIG. 8 shows a view of the HPRD with deflection rollers,

FIG. 9 shows a first tooth geometry of inner toothing,

FIG. 10 shows a first tooth geometry of outer toothing,

FIG. 11 shows a sequence of movement of the pins,

FIG. 12 shows a pin trajectory according to a second tooth geometry of agearwheel,

FIG. 13 shows the second tooth geometry of the gearwheel, and

FIG. 14 illustrates a method for determining a gear geometry,

FIG. 15 shows a cross section through a harmonic pin ring gear system inaccordance with a first embodiment,

FIG. 16 shows an enlargement of a section marked in FIG. 15,

FIG. 17 shows the course of the plane of intersection in FIGS. 18 and19,

FIG. 18 shows a first sectional view through the gear system in FIG. 15,

FIG. 19 shows a second sectional view through the gear system in FIG.15,

FIG. 20 shows the course of the plane of intersection in FIG. 21,

FIG. 21 shows a third sectional view through the gear system in FIG. 15,

FIG. 22 shows a force flow through the gear system in FIG. 15,

FIG. 23 shows a section of a further configuration based on the gearsystem in FIG. 15,

FIG. 24 shows a section of a further configuration based on the gearsystem in FIG. 15,

FIG. 25 shows a section of a further configuration based on the gearsystem in FIG. 15,

FIG. 26 shows a sectional view of a harmonic pin ring gear system,

FIG. 27 shows an exploded view of a reduction gear region of theharmonic pin ring gear system,

FIG. 28 shows a sectional view of a rotor assembly of the harmonic pinring gear system,

FIG. 29 shows a sectional drawing of the reduction gear region in FIG.27,

FIG. 30 shows an exploded view of an inner region of the harmonic pinring gear system, and

FIG. 31 shows a sectional view of a further harmonic pin ring gearsystem with a space for installing a change-speed gear system,

FIG. 32 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven sun wheel and follower hollow wheel,

FIG. 33 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven sun wheel and follower planetary carrier,

FIG. 34 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven hollow wheel and follower sun wheel,

FIG. 35 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven hollow wheel and follower planetary carrier,

FIG. 36 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven planetary carrier and follower sun wheel,

FIG. 37 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear with driven planetary carrier and follower hollow wheel,

FIG. 38 shows the harmonic pin ring gear system in FIG. 31 with aplanetary gear and a derailleur gear system, and

FIG. 39 shows a further harmonic pin ring gear system with a linear camgear system.

According to this description, a transmitter that draws a traction meansinto an outer gear or outer ring or inner gear or inner ring can, forexample, take the form of a flange of a rotor or a pair of deflectionrollers. The outer gear takes the form of one or more rings or diskswith outer toothing configured as internal toothing. The inner gear cantake the form of one or more rings or disks with an inner toothingconfigured as external toothing and the traction means takes the form ofa pin ring.

In the following, “drive side” refers to the side from which the rotor13 is driven and “driven side” means the side opposite the drive side.

FIG. 1 shows a Harmonic Pin Ring Drive (HPRD) 10 according to theapplication. The HPRD comprises a rotor 13 supported on a housing by aball bearing that is not shown here. An outer ring 8 of a cylindricalhousing part 9 arranged concentrically outside the rotor 13 comprises afirst outer toothing 6 formed as internal toothing on a first side. Asecond outer toothing 6′ formed as internal toothing is formed on asecond outer ring that is inserted into the cylindrical housing part 9on a side opposite the first side.

First inner toothing 5 configured as external toothing is formed on aperiphery of an inner ring 7 and arranged concentrically inside thefirst outer toothing 6. Second inner toothing 5′ configured as externaltoothing is formed on a periphery of a second inner ring 7′ and arrangedconcentrically inside the second outer toothing 6′ in a similar manner.

The inner toothing 5, 5′ and the outer toothing 6, 6′ are arrangedconcentrically to a central axis, wherein the inner toothing 5, 5′ isable to rotate about the central axis. In other embodiments the outertoothing 6, 6′ and/or the outer and the inner toothing are able torotate about the central axis depending on which set of toothing is thedriven toothing or, in the case of transmission, the drive toothing.

A flexible thin-section ball bearing 2 is fixed onto a specially formedflange 4 of the rotor 13. The flange can be formed as an oval or as asine-overlaid circular shape, for example. A flexible pin-retaining ring3 is arranged between the flexible thin-section ball bearing 2 and theouter toothing 6, 6′. The flexible pin-retaining ring 3 comprisesgrooves on an inside to receive pins 1 that are arranged equidistantlyon the pin-retaining ring 3 and held rigidly by the pin-retaining ring3.

FIG. 2 shows a view of the HPRD 10 from a driven side and FIG. 3 shows across section through the HPRD 10 along the cross-sectional line A-A.

The first inner toothing 5 is supported on the rotor 13 by a ballbearing that is not shown in FIGS. 2 and 3 for the sake of simplicity.The second inner toothing 5′ is fixed to a driven shaft, also not shownhere, that is supported outwards by ball bearings. The outer toothing 6,6′ is fixed in a stationary manner to a housing that is not shown here.

According to another embodiment the inner toothing 5, 5′ is stationarywhile the outer toothing 6, 6′ forms a follower. According to a furtherembodiment both the inner toothing 5, 5′ and the outer toothing 6, 6′form followers.

FIG. 4 shows the flexible ball bearing 2 and the pin-retaining ring 3with the pins 1. The pin-retaining ring together with the pins 1 is alsoreferred to as a pin ring. The flexible thin-section ball bearing has aflexible inner ring 14 and a flexible outer ring 23 between which balls26 are arranged.

The pins 1 are placed in receiving grooves 41 of the pin-retaining rings3 and are held against the thin-section ball bearing 2 by the contactpressure of the pin-retaining ring 3. The components can be assembledmanually, for example, by first placing the pin-retaining ring aroundthe thin-section ball bearing 2, then inserting pins 1 in widelyseparated positions, thereby defining the distance between thethin-section ball bearing 2 and the pin-retaining ring 3. The remainingpins are then inserted into the intermediate spaces.

FIGS. 7 and 8 illustrate a pin raceway 10 and resulting relationships. Adistinction must be made between the pin raceway 10 and the pintrajectory which indicates the movement of an individual pin in apreviously defined reference system. For a reference system that rotatestogether with the rotor 4, the pin trajectory runs along the pin raceway10. For reasons of clarity FIGS. 7 and 8 do not show any toothing.

The pin raceway 10 is determined by imagining a path through the centralaxes of all the pins (2). This path has a small axis 11 of length 2 band a large axis 12 of length 2 a offset at right angles. If thetransmitter is elliptical in shape, a is the length of the semi-minoraxis and b is the length of the semi-major axis of the ellipse.

The small axis and the large axis form the basis of the pitch circles ofthe gearwheels 5, 5′ and 6, 6′, wherein the small axis corresponds to adiameter of a pitch circle of the inner toothing 5, 5′ and the largeaxis corresponds to a diameter of a pitch circle of the outer toothing6. In the HPRD the pitch circle of a set of toothing runs through theflank lines that delimit the tooth flanks from the tooth base. Assuminggiven tooth shapes for the gearwheels 5, 5′ and 6, 6′, it is nowpossible to describe the gear function.

If, for example, the internal toothing 5, 5′ is held static and therotor 13 is rotated, a wave movement of the arrangement of pins 1 iscreated. This results in a relative movement of the outer toothing 6, 6′which rotates reduced in the same direction of rotation as the rotor 13.If the outer toothing 6, 6′ is held static, the inner toothing 5, 5′rotates reduced in the opposite direction to the rotor 13.

The total number of pins 1 must be two more than the number of teeth ofthe inner toothing 5, 5′ or two less than the number of teeth of theouter toothing 6, 6′. The difference in the number of teeth ingearwheels 5, 5′ and 6, 6′ is therefore four. In principle, tooth numberdifferences of multiples of four would also be possible.

In equations (1) to (3) below, R refers to the period of revolution ofthe rotor 1, F to the period of revolution of the flex output gear 7, Ato the period of revolution of the outer gear, I to the period ofrevolution of the inner gear, Zi to the number of teeth on the internaltoothing 5, 5′ and Za to the number of teeth on the outer toothing 6,6′. According to equations (1) to (3) the speed reduction ratios betweenthe individual components are as follows:

If the inner gear is held stationary, then

A/R=Za/(Za−Zi) or F/R=2*(Za/(Za−Zi))  (1)

Here all the elements rotate in the same direction.

If the outer gear is held stationary, then

I/R=Zi/(Za−Zi) or F/R=2*(Zi/(Za−Zi))  (2)

Here the inner gear and the flex-ring rotate in the opposite directionto the rotor.

If the flex-ring is held stationary, then

A/R=2*(Za/(Za−Zi)) or I/R=2*(Zi/(Za−Zi))  (3)

Here the inner gear rotates in the same direction as and the outer gearin the opposite direction to the rotor.

There follows an example calculation of the possible reduction steps,wherein in this case the rotor 13 always sets the input speed. Thenumber of teeth on the internal toothing is 156 and the number of teethon the external toothing is 160, giving a total of 158 pins.

If the inner gear is held stationary, then

A/R=160/(160−156)=40 or F/R=2*(160/(160−156))=80.

If the outer gear is held stationary, then

I/R=156/(160−156)=39 or F/R=2*(156/(160−156))=78.

If the flex-ring is held stationary, then

A/R=2*(160/(160−156))=80 or I/R=2*(156/(160−156))=78.

There are various possible ways of defining the pin raceway. Inprinciple, as described above, each pin raceway has a small axis x and alarge axis y offset at right angles, the ratio between themcorresponding to the number of teeth on the gearwheels 5, 5′ and 6, 6′.

Thus x/y=Zi/Za.

Moreover, the pitch of the arrangement of pins 1 in the pin-retainingring 3 must correspond to the pitch of the gearwheels 5, 5′ and 6, 6′.Thus the pin raceway is also defined by its arc length. For the arclength s of any pin raceway:

s=number of pins 1*pitch.

The circumference of the pin raceway less the circumference of a pin 1must therefore correspond exactly to the circumference of the ballbearing 2.

Three raceway variants are described below.

1. The elliptical raceway is defined by its two semi-axes, wherein thesemi-minor axis corresponds to the pitch circle radius of the internaltoothing 5, 5′ and the semi-major axis corresponds to the pitch circleradius of the external toothing 6, 6′.

2. The sine-overlaid circular shape is very similar to the ellipticalraceway and differs from it only very slightly in case of smalldifferences in axis. It is defined as follows. The central axis of asmall circle with a diameter according to the half value of thedifference between the large axis and the small axis revolves on thelarge circular path of the central circle between the two pitch circlesof toothing 5, 5′ and toothing 6, 6′ and in so doing rotates twice aboutits own axis while revolving about the central axis. Projecting a pointon the small circle to derive a path results in the sine-overlaidcircular shape.

3. The double eccentric cam raceway is a special shape that can be used,for example, where elastic deformation of the ball bearings 2 is notdesired or impossible due to the difference between the two axes of thepin raceway. In such a case the arrangement of the pins 1 is deflectedby two deflection rollers from the pitch circle of the internal toothing5, 5′ into the pitch circle of the external toothing 6, 6′. The axes ofrotation of the two deflection rollers are located symmetrically to thesmall axis on the large axis in relation to a notional ellipse.

FIGS. 7 and 8 show a view of two embodiments of an HPRD with deflectionrollers 15, 15′. In FIG. 7 the plane of intersection is offset rearwardsin the right half to show the toothing 5′, 6′.

FIG. 8 also shows a ball bearing 16 on which the deflection roller 15 ismounted and a ball bearing 17 on which a disk 18 with the internaltoothing 5 is mounted. It also shows elongated adjusting slots 19. Thedeflection rollers 15, 15′ can be tensioned by moving them along theadjusting slots 19.

The pin raceway 10 abuts a pitch circle of the inner toothing 5 at aninner contact region 20 and the pin raceway 10 abuts a pitch circle ofthe toothing 6 at an outer contact region. In an intermediate region 22the pin raceway 10 is approximately straight. In total there are twoinner contact regions 20, two outer contact regions 21 and fourintermediate regions such that the pin raceway comprises four regions inthe form of a segment of a circle and four straight regions. This pinraceway 10 is also referred to as a double eccentric cam pin raceway 10.

The deflection rollers 15, 15′ are mounted such that they are able torotate about an axis of rotation through their centres. Instead of theflexible ball bearing described above, it is the bearing of thedeflection rollers that takes up the slack of the pin ring in relationto the rotor 13. The axes of rotation of the deflection rollers 15, 15′are arranged eccentrically in relation to the central axis. FIG. 8 showsthe eccentric offset d.

It is advantageous to make the radius of the deflection rollers as largeas possible in order to achieve a large contact surface with the pinring and so even force distribution. According to the application, thedeflection rollers can be flat in construction and have recesses to keepthe weight of the deflection rollers low.

Instead of the deflection rollers, two blades with rollers on thesurface of the blades can also be used, wherein the blade is fixedrigidly to the rotor 13. In particular, the blade can be formed suchthat a contact surface extends between the blade and the pin ring overseveral pins.

Since in the HPRD the transmission of power is effected by pins 2 withcircular cross sections and they rotate slightly about their centralaxes as they move along the orbit determined by the rotor flange 4, thedistance between the tangential abutting face at the tooth of thegearwheels 5, 5′ and 6, 6′ and the axis of rotation of the pin 1 isalways constant.

Thus it is possible to design or calculate the tooth shape independentlyof the selected pin raceway such that all the pins 1 are constantly inmesh with a tooth of at least one of the gearwheels 5, 5′ and 6, 6′ andall the torque can be distributed between all the pins 2. As a result,the contact pressure at all the pins 2 and the gearwheels 5 and 6 isvery low. This in turn allows high efficiency, low wear and very goodpower density and thus an extremely compact design.

FIGS. 9 and 10 show a configuration of the tooth geometries for theinner toothing and the outer toothing according to the application.

The tooth geometry results from the sequence of movement of a pin 1within a reference system in which the gearwheel is at rest. The toothgeometry is the contour 25 of the moving centre point of the pin 1offset about the radius value of pin 1 which starts here, using theexample of the internal toothing 5, 5′, at the centre point of a toothbase 24. The centre point of a tooth base 24 lies at the intersection ofthe axis of symmetry 29 of a tooth base 24 and the pitch circle 30 ofthe inner toothing 5.

The pin trajectory 25 intersects exactly halfway through both the pitchcircle 40 of the outer toothing 6, 6′ and the line of symmetry 27 of thetooth and run, again symmetrically to the previous course to the endpoint, to the centre point of the adjacent tooth base 24. The toothshape is determined by the inner envelope of the pin profile 28.Moreover, FIG. 9 also shows a tip circle 32 of the outer toothing 6 toillustrate the distance between the teeth.

FIG. 10 shows the same configuration of the teeth of the outer toothing6. Elements corresponding to FIG. 9 are denoted by the same referencenumeral plus 10. For example, the contour is denoted by referencenumeral 35.

According to this application, a design of an HPRD comprises thefollowing steps, which are also shown in FIG. 14.

1) Definition of the desired reduction, for example 1:36.

2) Definition of the components to receive the output speed

-   -   Selection of the external toothing 6, 6′. In this case it may be        one of the gearwheels 5, 5′ or 6, 6′; in a HPRD-MULTI it may        also be a flexible output gear 7.

3) Determination of the number of teeth on the inner toothing 5, 5′ andthe outer toothing 6, 6′

-   -   Result according to the reduction formulae:    -   Zi=140 and Za=144.

4) Determination of the number of pins 1

-   -   Result according to the reduction formula: 142 pins 1.

5) Definition of the diameter of the pins 1

-   -   Example: Ø2 mm.

The dimensioning of the pin diameter determines the transmittabletorques which are in turn dependent on the choice of materials and thetoothing widths. The dimensions of all the components in the gear systemmust be dimensioned and matched with one another depending on therequirements.

6) Definition of the pitch of the gearwheels 5, 5′ and 6, 6′ and thepin-retaining ring

-   -   Example: 2.8 mm.

The pitch in an HPRD is usually the diameter of the pin 1 multiplied bythe pitch factor 1.4±7%, so here 2 mm x 1.4=2.8 mm. The number anddiameter of the pins 1 give a defined pin raceway length dependent onthe chosen pitch which must fit the outer circumference of the ballbearings 2 exactly.

7) Calculation of the arc length s of the raceway of the pin arrangement1 as described above.

-   -   Calculation: s=number of pins (1)*pitch, s=142*2.8 mm=397.6 mm.

8) Definition of the raceway variants of the pin arrangement 1

-   -   Example: ellipse.

9) Calculation of the raceway geometry of the pin arrangement 1

-   -   Here an elliptical geometry must be calculated with a semi-axis        ratio corresponding to the ratio of the number of teeth of the        gearwheels 5, 5′ and 6, 6′ and a circumference equal to the arc        length s=397.6 mm calculated in 7).

Determination of the geometry of the components. Once the racewaygeometry has been defined, the geometry of all the other parts can bederived from it.

10) Geometry of the ball bearing 2

-   -   The circumference of the ball bearing 2 corresponds to the inner        envelope of the pins 1 arranged evenly on the calculated raceway        geometry. The rest of the ball bearing 2, in particular in        relation to wall thicknesses of and the materials chosen for the        bearing inner and outer ring must be designed such that it is        sufficiently stable in terms of elasticity and variation in        stress over the required lifetime.

11) Geometry of the rotor 13

-   -   The initial geometry at the rotor flange 4 is the corresponding        inwardly offset geometry dependent on the cross section of the        ball bearing 2 and the diameter of the pin—here, for example,        the calculated elliptical raceway geometry, wherein the diameter        of the pin 1 and half the difference between the outer and inner        diameters of the ball bearing 1 must be subtracted from the        values of the semi-axes.

12) Geometry of the pin-retaining ring 3

-   -   The pin-retaining ring 3 must be designed such that it keeps all        the pins 1 constantly distributed equally tangentially on the        outer ring of the ball bearing 2. The rest of the pin-retaining        ring 3, in particular the wall thickness and choice of        materials, must be designed such that they are sufficiently        stable in terms of elasticity and variation in stress over the        required lifetime.

13) Geometry of the gearwheels 5, 5′ and 6, 6′

-   -   The nominal tooth shapes of the gearwheels 5, 5′ and 6, 6′        result from the corresponding envelopes after the pins 1 have        rolled through according to step 7) above.

The tooth shape can be determined from the pin trajectory of theindividual pins using the main normal vector of the accompanying tripod.A tangential vector to the path is given by:

$\frac{d\overset{\rightarrow}{x}}{ds} = {{\frac{d\overset{\rightarrow}{x}}{d\;\varphi}*\frac{d\;\varphi}{ds}} = {\left( {{{r^{\prime}(\varphi)}\begin{pmatrix}{\cos(\varphi)} \\{\sin(\varphi)}\end{pmatrix}} + {{r(\varphi)}\begin{pmatrix}{- {\sin(\varphi)}} \\{\cos(\varphi)}\end{pmatrix}}} \right)*\frac{d\;\varphi}{ds}}}$

where s is the arc length along the path and the relevant dependenceshould be inserted for r(φ), so for example the equation for an ellipseor a sine-overlaid circular shape. A normal vector if on the pintrajectory pointing towards the centre of curvature is given by thecross product:

$\overset{\rightarrow}{n} = {\begin{pmatrix}0 \\0 \\1\end{pmatrix} \times \frac{d\overset{\rightarrow}{x}}{ds}}$

This vector must be normalised to the radius of the pin and added to apoint on the pin trajectory to obtain a point on the tooth geometry oron the inner envelope of the pins from a point on the pin trajectory.The vector if normalised to 1 is also referred to as the main normalvector of the trajectory. The tooth shape is determined by the endpoints of the normal vectors that have been normalised to the radius ofthe pins. These end points describe an equidistant of the pin trajectoryof the distance of the pin radius. In case of curve overlaps, thesection of the curve lying furthest from the pin trajectory must bechosen.

According to a first method for determining the tooth profileillustrated in FIGS. 9 and 10, boundary conditions such as fulcrums, forexample, are derived from the pin trajectory and then used to determinea pin trajectory. According to the application, it is then possible todetermine the tooth shape using, for example, the main normal vector.

The tooth profile according to the application can be determined withreference to FIGS. 9 and 10 as follows. Semi-circular tooth bases with aradius corresponding to the pin radius are arranged at the distance ofthe pitch angle. Two fulcrums are determined by the circle centres oftwo adjacent tooth bases. A further fulcrum is determined by theintersection of the centre line between the adjacent tooth bases with acircumcircle about the rotor axis, wherein the circumcircle indicatesthe maximum deflection of the pins.

These three fulcrums can be used, for example, to set a half ellipse, aparabola or another quadratic polynomial. When using a half ellipse, thetooth shape runs perpendicularly into the tooth base to prevent bucklingat this point. The long axis of the ellipse is oriented along the axisof symmetry between the tooth bases such that the fulcrums correspond tothe end points of the small semi-axes and an end point of a semi-majoraxis.

The tooth shape shown in FIGS. 9 and 10 is particularly suitable forpins that are so large that the track covered by the circular crosssections of the pins intersects with itself, as shown in FIGS. 9 and 10.This is particularly the case if the diameter of the pins is comparablewith half the pin lift. In FIG. 9 the pin lift is the distance betweenthe pitch circle 40 of the outer toothing and the pitch circle 30 of theinner toothing.

According to this application, the teeth of the outer ring 6 arearranged so closely together that the distance between two radiallyopposite tooth bases is approximately twice the circumference of thepins. This means inter alia that all the pins are always in mesh. As apin 1 moves, the pin 1 is pressed into an opposite tooth base if it islocated above the point of a tooth. This situation is shown in FIG. 11.In FIG. 11 a direction of motion of the inner ring 5 is indicatedschematically by an arrow 43, a direction of motion of the outer ring isindicated schematically by an arrow 42 and a direction of motion of apin 1 from tooth base to tooth base is indicated schematically by arrows44.

According to a further method the tooth shape is determined almostexperimentally using a suitable CAD simulation program. Here aparameterised curve is predetermined for the tooth shape above asemi-circular tooth base. The parameters of this curve are then adjustedin the CAD simulation until the largest distance between a pin and thesurface of a tooth as it moves from one tooth base to the next exceeds apredetermined threshold value such as 10 μm, for example. In particular,the parameters can also be adjusted such that for all pins the largestdistance from a surface of a nearest tooth during a period of the CADSimulation does not exceed a predetermined threshold value such as 10μm, for example. This ensures that each of the pins is in contact withone of the teeth at all times.

A further tooth shape is obtained if a boundary condition is set as aresult of which the pins move uniformly on the pin raceway when thedrive revolves uniformly. For an oval transmitter this gives a pintrajectory as illustrated in FIG. 12 and a tooth shape as illustrated inFIG. 13. A region of an inner ring with this toothing is indicated bythe reference numeral 5′. The formulae for the oval and thesine-overlaid pin raceway are given below. The radii of the envelopes,i.e. the free parameters a and b or r₀−r_(ep) and r₀+r_(ep) must bedetermined according to step 7).

For the elliptical shape, the distance between the pin raceway and thecentre point at a fixed angle gives:

${r(t)} = \frac{b}{\sqrt{1 - {\epsilon^{2}\mspace{14mu}{\sin^{2}\left( {{\omega\; t} - \varphi_{0}} \right)}}}}$

wherein the phase angle is in the argument of the cosine function and ∈refers to the eccentricity, i.e. the quotient b/a. ω indicates theangular velocity of the rotor 13. When measuring from outside towardsthe centre point r′(t)=r₀−r(t) should be used accordingly.

For the sine-overlaid circular shape this gives:

r(t)=r ₀ −r _(ep)*cos(2(ωt−φ ₀)).

Here r₀−r_(ep) is the radius of the small envelope and r₀+r_(ep) theradius of the large envelope. The sine-overlaid circular shape can alsobe obtained by Taylor's development of the ellipse equation according tothe square of the eccentricity to the first power. This gives:

${r(t)} = {{b*\left( {1 + {\frac{\epsilon^{2}}{4}{\sin^{2}\left( {{\omega\; t} - \varphi} \right)}}} \right)} = {b*\left( {1 + \frac{\epsilon^{2}}{8} - {\frac{\epsilon^{2}}{8}{\cos\left( {{2\omega\; t} - \varphi} \right)}}} \right)}}$

Developments of the ellipsis equation to higher powers are also suitablefor determining a transmitter shape according to the application.

The trajectory of the pins in a polar coordinate representation nowresults from the following consideration. If t passes through the values0 to T, where T is the period of revolution of the rotor 13, r(t) givesthe pin raceway. A Pin 1 moves from one tooth base to the next withinhalf a revolution of the rotor 13. Thus t passes through the values 0 toT.2 in the angular pitch.

The angular velocity of the pins is a good approximation of constant.For a still more precise approximation a sinusoidally oscillatingcorrection term must be taken into account in the angular velocity. Inthe teeth ratios considered above, however, it makes only a few percentdifference. With an angular pitch of φ_(T)=2π/Z, where Z is the numberof teeth, this gives φ(t)=t/(T/2)*φ_(T) and thus ∘t(φ)=φ*T/2φ_(T).

If r(t) is determined by a function f(ωt−φ₀), the resulting pintrajectory r(φ) of a single pin is

${r(\varphi)} = {{f\left( {{\omega*\varphi*\frac{T}{2\varphi_{T}}} - \varphi_{0}} \right)} = {f\left( {{\varphi*\frac{Z}{2}} - \varphi_{0}} \right)}}$

or with φ₀=0 as a pin raceway compressed by a factor of Z/2.

A part of this pin trajectory and the associated movement of the pins isshown in FIG. 11 for an elliptical transmitter shape. For FIG. 12 theenvelope of the pins was calculated numerically using the main normalvector. This envelope determines the tooth geometry. The units of lengthin FIGS. 11 and 12 are chosen in arbitrary units but the same for bothaxes. In these units the pin radius is larger than one in FIG. 12 andequal to one in FIG. 13.

According to this method, too, the chosen pin size results in a pointedtooth shape though the flanks of the tooth base have a gradient of lessthan 90 degrees.

Described below with reference to FIGS. 15 to 23 are further embodimentsof gear systems that can be in used, in particular, in connection withone of the aforementioned tooth geometries in which all pins of atraction or pressure means are in contact with an inner and an outerring.

Below the directional descriptions “axial”, “radial” and “peripheral” or“along the circumference” refer to a central axis of rotation of a gearsystem which is also referred to as the central gear system axis. Acentral gear system axis is predetermined, for example, by the axis ofrotation of the rotor of a motor unit.

FIG. 15 shows a sectional view of a harmonic pin ring gear system 150,also referred to as a “harmonic pin ring drive”, according to a firstembodiment. A drive unit 107 and a gear system 108 are both mounted viaa gear ball bearing 109 and a drive ball bearing 110 on a crankshaft111, also referred to as a pedal bearing shaft 111. The drive unit 107comprises a control unit 112 and a motor unit 113, wherein a batterycontact 114 and an electronic control system 115 are provided in thecontrol unit 112.

The motor unit 113 comprises an internal rotor motor with a stator 116affixed to an inside of a pot-shaped housing part 117. Coil windings ofa stator coil of the stator 116 are connected to terminals of theelectronic control system 115.

A rotor shaft 118 of the motor unit 107 is mounted on a roller bearing119 comprising a first ball bearing 120 and a second ball bearing 121inside the stator 116. Affixed to the rotor shaft 118 are two rows ofpermanent magnets 122 located radially opposite the stator coil. Therotor shaft 118 is formed as a hollow shaft that extends in stagestowards the gear system 108 through an inner step and an outer step. Theouter step of the rotor shaft 118 encompasses a ring-shaped step on acam disk 104 of the gear system 108 such that the outer step of therotor shaft 118 engages frictionally with the ring-shaped step of thecam disk 104.

In the embodiment shown the cam disk 104, also referred to as a wavegenerator 104, is not supported inwards by a separate bearing but issupported on the motor side on the rotor shaft 118 and on the gear sideon an inner gear 105 of the gear system 108. Moreover, the cam disk 104is centred relative to the crankshaft 111 by the outer step of the rotorshaft 118. The outer circumference of the cam disk 104 has an oval shapesuch an elliptical or sine-overlaid circular shape, for example. Fixedonto the outer circumference of the cam disk 104 is a thin-section ballbearing 102 with a deformable inner ring 123 and a deformable outer ring124.

Radially outside the thin-section ball bearing 102 a motor-side pin ring103′ lies on the thin-section ball bearing 102 that has groove-shapedindentations in axial direction into which cylinder pegs 101 or pins 101are inserted. The cylinder pegs 101 engage in an outer gear 6 withinternal toothing 126 located radially outside the cylinder pegs 101.

The outer gear 106 is screwed to a projection of the pot-shaped housingpart 117 and to a gear cover 127, wherein the screws run in axialdirection through the gear cover, the outer gear 106 and a step of thepot-shaped housing part 117. The outer gear 106 is arranged in a firstregion radially outside the cam disk 104 and in a second region radiallyoutside an inner gear 105. The inner gear 5 is arranged radiallyopposite the outer gear 106, wherein the pins 101 engage in externaltoothing 125 of the inner gear 105 and internal toothing 126 of theouter gear 106.

A gear-side pin ring 103 is arranged axially opposite the motor-side pinring 103′ such that the outer gear 106 is located between the gear-sidepin ring 103 and the motor-side pin ring 103′. Both the gear-side pinring 103 and the motor-side pin ring 103′ comprise groove-shapedindentations in axial direction in which the pins 101 engage. The pins101 are supported in axial direction by a gear-side thrust washer 130and a motor-side thrust washer 131, wherein the gear-side thrust washer130 is arranged on the gear cover 127 and the motor-side thrust washer131 is arranged on the pot-shaped housing part 117. The motor-sidethrust washer 131 extends radially inwards to approximately the heightof the middle of the thin-section ball bearing 102.

The inner gear 105 is mounted via a roller bearing 132 inwards on aregion of the gear cover 127. A follower holder 133 is screwed onto anouter region 134 of the inner gear 105, wherein a region of the innergear 105 and the follower holder 133 encompass the outer ring of theroller bearing 132. An inner region 135 of the inner gear 105 is mountedon an outer freewheel clutch 136 with an inner ring formed on a hollowdriven shaft 137. The hollow driven shaft 137 is mounted radiallyoutwards on a 2-row ball bearing 138 on a region of the gear cover 127.A chain wheel adapter 139 is fixed radially outwards on the hollowdriven shaft 137.

The hollow driven shaft 137 is mounted via the ball bearing 109 on asleeve 140 arranged on the crankshaft 111. The sleeve 140 is connectedto the crankshaft 111 via a toothed spline shaft. The crankshaft 111 hasa spline shaft profile 169 that engages in a spline shaft profile 170 ofthe sleeve 140. The crankshaft 111 comprises a fixing region 171 for afirst pedal crank on a gear-side end and a fastening region 172 for asecond pedal crank on a motor-side end. For the sake of simplicity, thepedal cranks are not shown in FIG. 15.

Furthermore, the hollow driven shaft 137 is mounted on an innerfreewheel clutch 142 on an drive ring 144 arranged on the sleeve 140.

The outer freewheel clutch 136 and the inner freewheel clutch 142 arearranged or operated in such a manner in relation to one another that ina drive direction either the inner gear 105 or the crankshaft 111 iscoupled to the chain wheel adapter 139 depending on which one rotatesmore quickly in the drive direction.

The gear system 108 of the harmonic pin ring gear system 150 is sealedby shaft seals 145, 147, 149, 151. An inner gear-side shaft seal 145 isarranged adjacent to the inner freewheel clutch 142 and an outergear-side shaft seal 147 is arranged adjacent to the 2-row ball bearing138. An inner shaft seal 149 is arranged inside the gear system andadjacent to the outer freewheel clutch 136.

A motor-side shaft seal 151 its arranged adjacent to the drive ballbearing 110. The drive ball bearing 110 is arranged on a motor-side endof the crankshaft 111 between the crankshaft 111 and a cylindricalregion 152 of a cooling cover 154 arranged. The crankshaft 111 issupported radially outwards on the cooling cover 154 by the drive ballbearing 110.

According to the embodiment in FIG. 15, the gear system 108 isencapsulated against the control unit 112 such that the electronics ofthe gear system 108 are protected against leaking gear oil. Similarly,the electronics of the gear system 108 are encapsulated against theexterior. This encapsulation is achieved inter alia by means ofstationary housing parts that lie one on top of another in axialdirection, wherein 0-rings are provided as radial and axial seals at thetransitions to the exterior and the gear system interior.

The control unit 112 comprises a ring-shaped circuit board 156 thatcontains components of the control electronics. The ring-shaped circuitboard can be connected via the battery contact 114 to a battery which isnot shown in FIG. 1. The battery contact 114 is connected to the circuitboard 156 by a cylindrical peg 158 and a screw 159. The circuit board156 lies on a cooling pad 161 on the cooling cover 154. The coolingcover 154 comprises cooling ribs 162 that extend over an outer surfaceof the cooling cover 154.

FIG. 16 shows an enlarged section of FIG. 15 marked in FIG. 15 by anoval line. To the left of the gear-side pin ring 103′ and to the rightof the motor-side pin ring 103, the left- and right-hand sides of thepins 101 are shown in perspective view. The horizontal boundary lines ofthe pins 101 correspond approximately to the lateral boundaries of thegroove-shaped indentations of the pin ring 103, 103′ in which the pins101 are received.

As can be seen particularly clear from FIG. 16, the outer ring 106 hasone circumferential channel on the gear-system side and one on themotor-side, wherein an O-ring 163 is fitted into the gear-side channeland an O-ring 164 is fitted into the motor-side channel. The gear cover127 and the [sic] each have a ring-shaped projection that is fitted intothe corresponding ring-shaped channel such that the O-ring is locatedbetween the ring-shaped projection and the ring-shaped channel.

FIGS. 18 and 19 show sectional views along the plane of intersectionC-C. The plane of intersection C-C, which is shown clearly in FIG. 17,runs perpendicular to a central axis of rotation of the gear system 108through the thin-section ball bearing 102 and through the pot-shapedhousing part 117, looking in the direction of the gear system 108. Forthe sake of clarity, FIG. 19 omits the thin-section ball bearing 102shown in FIG. 18 in order to show the internal toothing 125.

In FIG. 19 guide lines show clearly that an offset of the pins 101 at anangle of 45 degrees represents half a tooth-to-tooth distance such thata full orbit gives an offset of 2 teeth. The guide lines correspond to asemi-major axis and to a semi-minor axis of the cam disk 104respectively. The offset shown in FIG. 19 results if the inner geartoothing 125 has two teeth fewer than the outer gear toothing 126. For amirror-symmetrical cam disk 104 differences in tooth numbers of amultiple of two are also possible, though in such cases the reduction issmaller.

The tooth shape and the dimensions of the external toothing 125 of theinner gear 105, the internal toothing 26 of the outer gear 106 and thepins 101 are configured such that each of the pins 101 is in contactwith both the internal toothing 26 and the external toothing 125.

As shown in FIG. 18, the pins 101 lie radially inwards on the outer ring124 of the thin-section ball bearing 102 that is deformed outward by theoval shape of the cam disk 104 along a semi-major axis. The pins 101 arereceived in groove-shaped indentations of the motor-side pin ring 103that are shown in section in the view in FIG. 18. On the upper and lowersides the points of the internal toothing 125 that project inwardsbeyond the motor-side pin ring 103 are shown.

FIG. 21 shows a sectional view along the plane of intersection D-D. Theplane of intersection D-D, which is shown clearly in FIG. 20, runsperpendicular to the central axis of rotation of the gear system on themotor-side from the inner gear 105 through the cam disk 104, thethin-section ball bearing 102 and the outer gear 106, looking towardsthe gear system 108. The plane of intersection D-D is arranged somewhatfurther towards the motor side than the plane of intersection C-C inFIGS. 17 to 19.

The following explains a force flow through the gear system in greaterdetail with reference to FIGS. 15 and 22. FIG. 22 shows a force flowfrom the rotor shaft 118 to the chain adapter 139 and a force flow fromthe sleeve 140 to the chain adapter 139 by means of arrows. FIG. 15shows a force flow from the first crank to the sleeve 140 and from thesecond crank to the sleeve 140 by means of arrows.

While the motor unit 113 is in operation the power electronics on thecircuit board 156 of the control unit 112 is supplied with electricalcurrent via the battery contact 114. The electronics of the control unit112 generate a current in the stator coil of the stator 116. Theresulting magnetic field of the stator coil exerts a force on thepermanent magnets of the rotor shaft 118, thereby driving the rotorshaft 118. In one embodiment the electronics generate a three-phaseelectric current by pulse width modulation that is conducted by threestator coils of the stator 116 which are insulated from one another.

A torque of the rotor shaft 118 is transferred to the cam disk 104. Thecam disk 104, the thin-section ball bearing 102 fixed to it and the twopin rings 103, 103′ transform the torque into a radial force that istransferred to the pins 101. Here the thin-section ball bearing 102exerts a compression force on the pins 101 that acts radially outwards,and the pin rings 103, 103′ exert a tractive force on the pins 101 thatacts radially inwards. At the stationary internal toothing 126 of theouter gear 106, the radially outward directed compression force on thepins 101 is deflected into a force acting along the circumference on thestationary internal toothing 126 and into a counterforce acting alongthe circumference on the pins 101.

At the external toothing 125 of the inner gear 105, the radially actingtraction force on the pins 101 is deflected into a force acting alongthe circumference on the inner gear 105. Moreover, the counterforceacting on the pins 101 is also transferred from the outer gear 106 viathe pins 101 to the inner gear 105.

In a harmonic pin ring gear system according to FIGS. 15 to 23 atransmitter and external toothing 125 of an inner gear 105 are eacharranged at least partially in axial direction inside the outer gear 106such that a first radial force flow 167 runs in a straight directionfrom the transmitter via the pins 101 to the internal toothing 126 ofthe outer gear 106 and a second radial force flow 168 runs in a straightdirection from the internal toothing 126 of the outer gear 106 via thepins 101 to the external toothing 125 of the inner gear 105. Inparticular, according to this description the first radial force flow167 and the second radial force flow 168 can be perpendicular to thecentral gear system axis 128.

This course of the radial force flow is favourable for avoiding bendingand tilting torque on the pins 101 and for achieving an even load on thegearwheels. This force flow differs from a force flow in a gear systemof the type disclosed in patent AT 372 767, for example. In a gearsystem according to AT 372 767 a force flow runs from an eccentric camvia a ball bearing and a bearing ring to an end region of a roller chainthat is not located axially outside an outer gear. As a result, in agear system according to AT 372 767 a bending torque acts on the rollersof the roller chain in particular when a compression force is exerted onthe rollers.

In FIG. 22 a first region 165 of the outer gear 106 in which theinternal toothing 126 of the outer gear 106, the pins 101 and theexternal toothing 125 of the inner gear 105 overlap in axial directionis indicated by a first curly bracket and a second region 166 of theouter gear 106 in which the internal toothing of the outer gear 106, thepins 101 and an outer circumference of a transmitter overlap in axialdirection is indicated by a second curly bracket. The cam disk 104, theinner ring 123 and the outer ring 124 of the thin-section ball bearing102 are located at least partially inside the second region 166 in axialdirection.

In addition, located inside the second region 166 is an inner supportregion in which the ball bearing balls of the thin-section ball bearing102 are in contact with the inner ring 123 of the thin-section ballbearing 102 and an outer support region in which the ball bearing ballsof the thin-section ball bearing 102 are in contact with the outer ring124 of the thin-section ball bearing 102. If, for example, cylindricalroller elements with a broader support region in axial direction areused rather than ball bearing balls, the inner and outer support regionof the roller elements can also be partly located axially inside thesecond region 166.

The aforementioned transmitter can in particular comprise an oval-shapedcam disk 104 and a deformable thin-section ball bearing 102 as shown inFIGS. 15 to 23. However, the transmitter can also comprise one or moreeccentric cams as shown in FIGS. 7 and 8. These eccentric cams can inturn have ball bearings to avoid friction, though they do not need to bedeformable. When using eccentric cams, the eccentric cams and whereappropriate the ball bearings or roller bearings are located at leastpartially in axial direction inside the outer gear.

The first region 165 and the second region 166 can be essentiallydirectly adjacent in axial direction as shown in FIG. 22 or they can bea distance apart. It is possible to provide a distance between the innergear 104 and the thin-section ball bearing. In the example in FIG. 22, adistance is provided between the external toothing 125 of the inner gear105 and the outer ring 124 of the thin-section ball bearing 102 by therounded shape of the outer ring 124.

The torque of the inner gear 105 is transmitted via the outer freewheelclutch 136 and the hollow driven shaft 137 to the chain wheel adapter139 where it can be transferred via a drive means such as a chain wheeland a chain, for example, to an element to be driven such as a wheelhub, for example.

This torque curve is similar to the torque in WO 2010/1131115 to whichreference is made here. The “inner wheel” to which it refers correspondsto the inner gear or inner gears with external toothing in thisdescription, while the “outer wheel” to which it refers corresponds tothe outer gear with internal toothing in this description. The “tractionmeans” to which it refers corresponds to the pins, in particular the pinring with the pins, in this description and the transmitter to which itrefers corresponds to the oval cam disk and the thin-section ballbearing or to the eccentric cam with the ball bearing placed on it or tothe double eccentric cam with the ball bearings placed on it. A pin ring103, 103′ with pins 101 corresponds both to a traction means and apressure means, wherein a traction force is transmitted essentially bythe pin ring 103, 103′ and a compression force is transmittedessentially by the pins 101.

In a similar manner to WO 2010/1131115 and as shown in FIG. 18, in agear system according to this description the inner gear can, forexample, also be fixed in a stationary manner to a housing and the outergear can be connected to a driven shaft or form part of the drivenshaft.

According to WO 2010/1131115 a chain is pressed by a transmitter into anouter ring and drawn into an inner ring. In contrast, according to thisapplication an arrangement of pins is pressed by a cam disk or one ormore eccentric cams into internal toothing of an outer gear and drawninto external toothing of an inner gear by a pin ring.

Further embodiments with a similar torque curve are disclosed in WO2012/046216 to which reference is also made here. WO 2012/046216 showsboth arrangements in which inner ring, outer ring, drive means andtransmitter are located in one plane and arrangements in which thetransmitter is arranged in another plane to the inner and outer rings,as illustrated in FIGS. 23, 25, 41, 42 and 43 of WO 2012/046216, forexample. In particular in an embodiment in which the transmitter is notdeformed, as with an eccentric cam, a ball or roller bearing can bearranged on an inside when viewed radially, as shown in FIG. 37 of WO2012/046216, or on an outside, as shown in FIG. 41 of WO 2012/046216.

FIGS. 23 to 25 show enlarged sections of gear systems constructed in amanner similar to the gear system shown in FIG. 15. For the sake ofsimplicity, gear system parts which correspond to gear system parts ofthe gear system shown in FIG. 15 have been omitted. FIG. 23 shows anangular position in which a pin 101 is located in the tooth base of theexternal toothing 125 of the inner gear.

Unlike that shown in FIG. 15, the gear system in FIG. 23 comprises onlya motor-side pin ring 103. According to the embodiment in FIG. 22, atraction force is transmitted from the pin ring 103 via the pins 101 tothe axially opposite side of the pins such that the pins 101 are pressedinto the external toothing 125 of the inner gear 105.

FIG. 24 shows an enlarged section of a gear system in which the pins areplaced in a motor-side pin ring 103 and a gear-side pin ring 103′. Thusin the sectional view of FIG. 23 the motor-side pin ring 103 and thegear-side pin ring 103′ are located radially inside and outside the pins101.

FIG. 24 shows an enlarged section of a gear system in which a third pinring 103″ is arranged in a channel 173 of the outer gear 106. In thisconfiguration the outer gear 106 comprises a motor-side part 106′ and agear-side part 106″ that are connected to one another. In a geararrangement the third pin ring can be inserted into the channel 173before the parts 106′ and 106″ of the outer gear 106 are connectedtogether by screwing, for example.

The embodiments in FIGS. 22 to 24 can also be combined, for example byproviding only one motor-side pin ring 103 into which the pins areplaced.

Moreover, it is also possible to provide a configuration in whichsupport regions for the pin rings 103 and 103′ are available on axiallyopposite regions in the outer ring 106 and in which the pin rings 103,103′ are arranged in axial direction wholly or partially inside theouter gear 106. The outer gear 106 can also be configured in two partsinstead of one, for example, wherein a dividing plane runs perpendicularto the central gear system axis.

Furthermore, the outer gear 106 and/or the inner gear 105 can also bestructured in individual segments designed as segments of a circle. Thedesign of the inner or outer gear 105, 106 shown in FIGS. 15 to 23 as aring formed as one part in circumferential direction offers greaterstability and dimensional stability while a design with circularsegments makes for simpler assembly.

Instead of the oval cam disk 104, the gear systems in FIGS. 15 to 24 canalso have a single or double eccentric cam similar to that shown inFIGS. 7 and 8.

FIGS. 26 to 30 show a further embodiment of a harmonic pin ring gearsystem 150′. Similar components have the same reference numerals as inthe embodiment in FIGS. 15 and 22 or reference numerals with anapostrophe.

FIG. 26 shows a cross sectional view of the harmonic pin ring gearsystem 150′. FIG. 26 shows the left-hand side of a drive side and theright-hand side of a driven side of the harmonic pin ring gear system.

A stator 116 of a stator assembly of the harmonic pin ring gear system150′ is arranged in a motor housing 175. The stator 116 comprises threeseparate coils for connection to the three phases of a three-phase ACgenerator. The three-phase AC generator is designed as power electronicsand arranged on a circuit board 156, wherein the circuit board 156 isfixed in a motor housing 175 on the drive side. The three coils of thestator 116 are connected to the three-phase AC generator by threeplug-in connectors 176, one of which is shown in FIG. 1.

A rotor 129 equipped with permanent magnets is arranged radially insidethe stator 116. The rotor 129 is arranged on a rotor shaft 118 designedas an elongated bush. The rotor shaft 118 is mounted on the drive sideoutwards in a drive-side rotor ball bearing 121′, wherein an outer ringof the drive-side rotor ball bearing 121′ is arranged in a cylindricalrecess of the motor housing 175.

The rotor shaft 118 is mounted on the driven side in a driven-side rotorball bearing 120′ radially outwards in an inner gear 105. A hollow shaft177 of the inner gear 105 is mounted radially outwards on an inner gearball bearing 132′ on a housing cover 127, wherein the inner gear ballbearing 132′ is offset in axial direction relative to the driven side inrelation to the drive-side rotor ball bearing 120′.

A cam disk 104 is arranged on the rotor 129. The cam disk 104 iselliptical or ellipsoid in shape. A flex ball bearing 102 orthin-section ball bearing is shrunk onto the cam disk 104 in which aninner ring 123 and an outer ring 124 are deformable.

Instead of the ellipsoid cam disk 104 it is also possible to fit twocircular disks with offset centre points in a manner similar to thatshown in FIG. 8. In this case the circular disks can be mounted insidesuch that they can rotate on ball bearings and the flex ball bearing 102can therefore be omitted.

To differentiate more clearly, the ring that receives the pins isreferred to below as the pin ring and the entirety of the pins and thepin-retaining ring as the pin ring.

A pin ring 103 with pins 101 lies on the flex ball bearing 102, whereinthe pins 101 are held in cylindrical recesses on the inside of apin-retaining ring 178. The cylindrical recesses run in axial directionand are open to the inside in radial direction. The pins 101 of the pinring 103 protrude in axial direction on both sides beyond the flex ballbearing 102 and beyond the pin-retaining ring 178.

Together the cam disk 104 and the flex ball bearing 102 form atransmitter that transforms a torque into a radial force.

Instead of a flex ball bearing with flexible inner and outer ring it isalso possible to use a wire roller bearing or a flex ball bearingwithout an outer ring, wherein the function of the outer ring it assumedby a pin-retaining ring designed for the purpose.

The housing cover 127 is screwed onto the motor housing 175 withmounting screws 179 on the driven side of the motor housing 175.Furthermore, a drive-side outer gear 106′ and a driven-side outer gear106 are fixed by the mounting screws 179 between the housing cover andthe motor housing, wherein spacer sleeves 180 are provided between thedrive-side outer gear 106′ and the driven-side outer gear 106 throughwhich the mounting screws pass. An O-ring 185 is inserted radiallyoutside between the driven-side outer gear 106 and the housing cover127.

Screwed to the housing cover is a cover ring 203. The cover ring 203covers supporting struts of the housing cover 127 and provides a smoothsurface. This can be advantageous, for example, if a drive means slipsoff and gets in between the chain wheel adapter 139 and the motorhousing 175.

The drive-side outer gear 106′ and the driven-side outer gear 106 arearranged outside the cam disk 104 and the flex ball bearing 102 in axialdirection. The drive-side outer gear 106′ is located in radial directionopposite the regions of the pins 101 that protrude beyond thepin-retaining ring 178 in axial direction on the drive side. Thedriven-side outer gear 106 is located in radial direction opposite theregions of the pins 101 that protrude in axial direction beyond thepin-retaining ring 178 on the driven side.

A drive-side thrust ring 130 is arranged in the motor housing 175 on thedrive side such that it is located opposite the drive-side front facesof the pins 101 in axial direction. Similarly, a driven-side thrust ring131 is arranged on the driven side in the motor housing 175 such that itis located opposite the driven-side front faces of the pins 101 in axialdirection.

A driven shaft 137 is arranged radially inside the hollow shaft 177 ofthe inner gear 105, wherein a motor freewheel 136 is arranged betweenthe hollow shaft 177 of the inner gear 105 and the driven shaft 137. Asupport shaft 174 is placed on the drive side in radial directionoutside on the driven shaft 137. The support shaft 174 is mountedradially outwards in a drive-side driven ball bearing 181 that isinserted into a cylindrical indentation or shoulder of the motor housing175.

The driven shaft 137 is mounted radially outwards in a drive-side drivenball bearing 138′ that is inserted into a cylindrical recess or shoulderof the motor cover 127. The drive-side region of the driven shaft 137protrudes in axial direction beyond the housing cover 127. A chainwheeladapter 139′ is placed on the driven shaft 137.

Arranged inside the driven shaft 137 that is configured as a hollowshaft is a pedal shaft 111. An anti-friction bush 182 is arranged on thedriven side of the pedal shaft 111. A measuring shaft 140 is arranged onthe pedal shaft 111 such that on the drive side it is connected to thepedal shaft via feather keys 183 such that it is unable to rotate, andon the driven side it lies on a shoulder of the anti-friction bush 182.The anti-friction bush 182 is mounted on a driven-side pedal shaft ballbearing 109 radially outwards in the driven shaft 137. The measuringshaft 140 is mounted on a drive-side pedal shaft ball bearing 110radially outwards on the motor housing 175.

Two adjacent pedal shaft freewheels 142, 143 are arranged between themeasuring shaft 140 and the driven shaft 137 in the drive-side directionfrom the driven-side pedal shaft ball bearing 109. By using twofreewheels 142, 143 arranged adjacent to one another the measuring shaft140 is supported on a wider region relative to the driven shaft 137 thanif only one single freewheel is used. Instead of two freewheels it isalso possible to incorporate a single freewheel and an adjacent rollerbearing such as a needle roller bearing, for example.

A coil body 184 is arranged in the region between the rotor shaft andthe measuring shaft 140. The coil body 174 is fixed to the motor housing175 on the drive side and located a distance from the rotor shaft 118and the support shaft 174 in radial direction. A measurement connectionof the coil body 184 is run out of the coil body 184 on the drive sideand connected to the motor electronics. The support shaft 174encompasses the coil body 184 along a greater part of the axial extentof the coil body 184 and thus shields the torque sensor with the coilbody 184 and the measuring shaft 140 against electromagnetic radiationof the stator 116, thereby improving torque measurement.

The measuring shaft 140 and the coil body 184 are components of amagnetostrictive torque sensor. The magnetostrictive torque sensor is acontactless torque sensor in which, unlike a torque sensor with straingauges on the measuring shaft, no slip rings are required and in whichthe region through which the current flows can be fixed to the housing.

On the driven side of the driven-side pedal shaft ball bearing 109 aninner shaft seal ring 145 is inserted between the pedal shaft 111 andthe driven shaft 137 relative to the driven-side pedal shaft ballbearing 109. Furthermore, an outer shaft seal ring 147 is arrangedbetween the driven shaft 137 and the housing cover 127 in relation tothe driven-side driven ball bearing 138′.

During operation an input torque that is converted into radial force bythe cam disk 104 and the flex ball bearing 201 is transferred by thestator 116 through electromagnetic force action to the rotor 129 and therotor shaft 174. This radial force is converted at the tooth flanks ofthe outer gears 106, 106′ and the inner gear 105 into an output torque,wherein the inner gear 105 is driven. The output torque is greater thanthe input torque by the reduction ratio.

Unlike with the embodiment in FIGS. 15 and 22, in the embodiment inFIGS. 26 to 30 a drive-side outer gear 106′ and a driven-side outer gear106 are provided and the cam disk 104 is arranged centrally in axialdirection between the drive-side outer gear 106′ and the driven-sideouter gear 106. This provides improved support for the tilting torqueacting on the pins 101 of the pin ring 103 due to radially acting forcesof the transmitter 102, 104.

Moreover, a support shaft 174 that is connected to the driven shaft 137is designed as an elongated bush and the rotor shaft 118 is alsodesigned as an elongated bush. The greater axial extension of the shafts118, 137, both ends of which are supported outwardly in ball bearings120′, 121′ or 138′, 110, results in improved support for the tiltingtorque compared to the arrangements in FIGS. 15 and 22. In this respectsee the ball bearings 120, 121 or 138, 110.

In the embodiment in FIGS. 26 to 30 the two protruding ends of the pins101 are supported stably and symmetrically in relation to the centre ofthe pin ring 103 on the outer toothing formed by the internal toothingof the outer gears 106, 106′ which are mounted rigidly in the motorhousing 175. This results in good support against displacement of thepin 101 due to the induction of forces via the pin-retaining ring 178.

The inner toothing formed by the external toothing of the inner gear 104lies opposite one of the other sets of toothing, in particular oppositethe driven-side outer toothing in the outer gear 106, and thus providesthe output torque in particular via those pins 101 that abut both theinner toothing and the outer toothing.

FIG. 27 shows an exploded view of a gear system 108 of the harmonic pinring gear systems 150′ in FIG. 26.

As can be seen particularly clearly in this view, the pins 101 lie intransverse grooves 99 in the pin-retaining ring 178 that are designed asindentations with an essentially semi-circular cross section. Thus onone side of their circumference the pins 101 lie in the transversegrooves in the pin-retaining ring 178 and on the other side of theircircumference they lie on the outer ring of the thin-section ballbearing 102 an.

FIG. 28 shows a sectional view of the gear system 108 in FIG. 27 in itsassembled state. For the sake of simplicity, only the region of the pins101 protruding beyond the on the drive side is shown here.

FIG. 29 shows a cut-open three-dimensional view of the gear system 108in FIG. 27. Here the semi-minor axis of the elliptical cam disk 104 ispointing upwards. In the region of the semi-minor axis the pins 101 abutthe external toothing of the inner gear 105 while in the region of thesemi-major axis offset at right angles to it they abut the innertoothing of the outer gears 106, 106′. The dimensions of the gearwheels,pins 101 and cam disk 104 are selected such that the pins 101 are alwayssupported on at least one tooth.

FIG. 30 shows an exploded view of the harmonic pin ring gear systems150′ in FIG. 25.

On a driven-side region the driven shaft 137 comprises roundindentations 186 that are arranged equidistantly on the circumference ofthe driven shaft 137. The driven-side region of the driven shaft 137protrudes in axial direction beyond the housing cover. The chainwheeladapter 139′ not shown in FIG. 5 is placed on the driven shaft 137 suchthat round projections or channels of the chainwheel adapter 139′ engageradially from the outside in the round indentations 186 of the drivenshaft 137.

The nine screws 179 in FIG. 30 pass through nine screw holes in thehousing cover 127, the driven-side outer gear 106 and the drive-sideouter gear 106′ and are supported on washers 187 on the housing cover127. In a first assembly step they are tightened only slightly. Theouter gears 106, 106′ and the housing cover 127 are thus held in theirposition in relation to the central axis of the gear system by afriction fit only.

The outer gears 106, 106′, in particular, have clear and intentionalradial play in this position. In a further assembly step the position inthe motor housing 175 is adjusted by starting the gear system so that itmoves into a compensating position when the internal toothing of theouter gears 106, 106′, the external toothing of the inner gear 105 andthe pins 101 adjust to one another. Only then are the screws tightenedup and the position of the outer gears 106, 106′ thereby permanentlyfixed.

According to a special embodiment the internal toothing of the outergears 106, 106′ and the external toothing of the inner gear 105 aremanufactured using inexpensive non-hardened and non-tempered gear steel.As a result the gear system runs in more quickly after manufacture. Asthe overwhelming majority of the pins abut both the external and theinternal toothing and thus contribute to the transmission of the torque,according to this embodiment a material with lower strength can be used.According to a further embodiment the gearwheels are made of plastic.

Particularly good torque transmission results if no more than four pins101 do not contribute to the transmission of torque, namely those pins101 located precisely in the prolongation of the semi-minor orsemi-major axis of the cam disk and in the tooth base of the innertoothing or the outer toothing.

A method for assembling the harmonic pin ring gear systems 150′ isdescribed below. In a first assembly step the pins 101 are arrangedaround the flex ball bearing 102 and the pin-retaining ring 178 is fixedonto the flex ball bearing 102 such that the pins come to rest in thegroove-shaped indentations of the pin-retaining rings 178.

In a further assembly step the rotor 129 is pressed onto the rotor shaft118 and the cam disk 104 is also pressed onto the rotor shaft 118 on anopposite side. An axial position of the rotor 129 is adjusted with twospacer washers that are arranged on the drive side of the rotor 129.

The motor freewheel 136 and the drive-side rotor ball bearing 120′ areinserted into the inner gear 105. The support shaft 174 is placed on thedriven shaft 137 and the shaft seal ring 145 is inserted into the drivenshaft 137. Moreover, the driven-side follower ball bearing 138′ and theinner gear ball bearing 132′ are inserted into the housing cover 127.

Furthermore, the inner gear 105 with the driven-side rotor ball bearing120′ and the motor freewheel 136 are placed on the support shaft 174from the drive side. The housing cover 127 with the ball bearings 132′,138′ is placed on the inner gear 105 from the driven side. Thedriven-side outer gear 106, the thrust ring 131 and an O-ring are placedon the housing cover 127 from the drive side.

The rotor shaft 118 with the components arranged on it is inserted intothe driven-side rotor ball bearing 120′ from the drive side, and thedriven shaft 137 is inserted into the rotor shaft 118 from the driveside.

The stator 116, the drive-side follower ball bearing 181 and thedrive-side rotor ball bearing 121′ are inserted into the motor housing175 from the driven side.

The spacer sleeves 180 and the drive-side outer gear 106′ are placed onthe driven-side outer gear 106 from the drive side. Spacer washers 187are placed on the screws 179 and the screws 179 are passed from thedriven side through the housing cover 127, the driven-side outer gear106, the spacer sleeves 180 and the drive-side outer gear 106′ intoscrew holes of the motor housing 175 and tightened slightly.

The motor electronics and a drive-side shaft seal ring 151 are thenassembled in a cooling cover 201 arranged on the drive side.

A drive-side shaft seal ring 151 is inserted into a cooling cover 201.The circuit board 156, to which a power supply connector 202 is fixed,is screwed to the cooling cover 201, wherein the power supply connector202 is inserted through an upper opening of the cooling cover 201.

Assembly of a pedal shaft assembly comprises the following assemblysteps. The measuring shaft 140 and anti-friction bush 182 are placed onthe pedal shaft 111 and the pedal shaft freewheels 142, 143 are placedon the measuring shaft 140. The driven-side pedal shaft ball bearing 109is placed on the anti-friction bush 182. The measuring shaft 140 withthe pedal shaft freewheels 142, 143 is inserted into the driven shaft137 from the drive side. The coil body 184 is inserted between themeasuring shaft 140 and the support shaft 174 from the drive side. Thepedal shaft assembly is inserted into the motor housing 175.

Then the cooling cover 202 is screwed onto the motor housing 175,wherein an O-ring is provided between the cooling cover 202 and themotor housing 175. A spacer ring is screwed onto the housing cover 127,the chainwheel adapter 139′ is inserted into the round notches 186 ofthe driven shaft 137 and a retaining ring is bent and inserted into agroove that runs at an angle to the round notches.

The motor housing 175 is screwed to a vehicle frame of a vehicle notshown in FIGS. 26 to 30 and a battery connector of the vehicle that isnot shown is connected to the power supply connector 202 of the harmonicpin ring gear system 150′.

FIG. 31 shows a further harmonic pin ring gear system 150″ that issimilar to the harmonic pin ring gear system of FIG. 26, wherein a space188 for installing a gear system 189 is arranged between the drivenshaft 137 and the chainwheel adapter 139′. A harmonic pin ring gearsystem according to this description can be built so as to save space inaxial direction so that with a lateral distance that is predetermined bya typical distance between pedals there is still sufficient spaceavailable for a gear system.

Similar components have the same reference numerals as in the embodimentin FIGS. 15 and 22 or reference numerals with apostrophes. For the sakeof simplicity, some of the components already referenced in FIG. 26 arenot numbered again here.

An output shaft 190 is arranged concentrically outside the driven shaft137 and mounted on a follower ball bearing 191 inside the motor housing175. An input of the gear system 189 is connected to the driven shaft137 and an output of the gear system 189 is connected to the outputshaft 190. The gear system 189 is preferably configured as a switchablegear system.

FIGS. 32 to 38 show various embodiments in which the gear system 189 isdesigned as a planetary gear.

The gear system according to FIG. 31 has differences in arrangementcompared to the gear system in FIGS. 26 to 30 which serve inter alia toprovide sufficient space for the installation space 188. The pedalbearing shaft 111 is supported directly on the housing on the drive sidevia a somewhat larger ball bearing 110.

On the driven side, the embodiment in FIG. 31 shows no outward supportfor the inner gear 105 or the driven shaft 137. The inner gear 105 canbe supported outwardly by a ball bearing on the housing 175 as in FIG.26 or it can be supported on a gear system part of the gear system 189.Similarly, the driven shaft 137 can be supported outwardly by a ballbearing on the motor housing 175 or on the housing cover 127 or it an besupported outwardly on a gear system part of the gear system 189.

A single pedal shaft freewheel 142 is provided instead of two pedalshaft freewheels 142, 143. The measuring shaft 140 is fixed to the pedalshaft 111 on the driven side and a widened support region for themeasuring shaft 140 on the pedal shaft 111 is provided instead of ananti-friction bush. The pedal shaft freewheel does not lie directly onthe measuring shaft 140. Instead a ring-shaped component is providedbetween the measuring shaft and the driven shaft 137. The driven-sidefollower ball bearing 138′ is arranged axially inside the pedal shaftfreewheel 142.

FIG. 32 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear in which

-   -   a sun wheel 192 having external toothing 205 is connected to the        driven shaft 137,    -   a planetary carrier 193 on which the planetary gears 195 are        mounted is connected to the motor housing 175,    -   a hollow wheel 194 having internal toothing 204 is connected to        the output shaft 190.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the hollow wheel 194 and themotor housing 175 and a second clutch is arranged between the sun wheel192 or with the driven shaft 173 and the hollow wheel 194. By looseningthe first clutch and tightening the second clutch the driven shaft 173is connected to the output shaft 190.

FIG. 33 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear, in which

-   -   a sun wheel 192 is connected to the driven shaft 137,    -   a planetary carrier 193 on which planetary gears 195 are mounted        is connected to the output shaft 190,    -   a hollow wheel 194 is connected to the motor housing 175.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the planetary carrier 193and the motor housing 175 and a second clutch is arranged between theplanetary carrier 193 and the hollow wheel 194. By loosening the firstclutch and tightening the second clutch the driven shaft 137 isconnected directly to the output shaft 190.

FIG. 34 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear designed in which

-   -   a sun wheel 192 is connected to the output shaft 190,    -   a planetary carrier 193 on which the planetary gears 195 are        mounted is connected to the motor housing 175,    -   a hollow wheel 194 is connected to the driven shaft 137.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the planetary carrier 193and the motor housing 175 and a second clutch is arranged between thesun wheel 192 and the hollow wheel 194. By loosening the first clutchand tightening the second clutch the driven shaft 137 is connecteddirectly to the output shaft 190.

FIG. 35 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear in which

-   -   a sun wheel 192 is connected to the motor housing 175,    -   a planetary carrier 193 on which the planetary gears 195 are        mounted is connected to the output shaft 190,    -   a hollow wheel 194 is connected to the driven shaft 137.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the sun wheel 192 and themotor housing 175 and a second clutch is arranged between the planetarycarrier 193 and the hollow wheel 194. By loosening the first clutch andtightening the second clutch the driven shaft 173 is connected directlyto the output shaft 190.

FIG. 36 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear in which

-   -   a sun wheel 192 is connected to the output shaft 190,    -   a planetary carrier 193 on which the planetary gears 195 are        mounted is connected to the driven shaft 137,    -   a hollow wheel 194 is connected to the motor housing 175.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the hollow wheel 194 192 andthe motor housing 175 and a second clutch is arranged between theplanetary carrier 193 and the sun wheel 192. By loosening the firstclutch and tightening the second clutch the driven shaft 173 isconnected directly to the output shaft 190.

FIG. 37 shows the harmonic pin ring gear system in FIG. 31, wherein thegear system 189 is designed as a planetary gear in which

-   -   a sun wheel 192 is connected to the motor housing 175,    -   a planetary carrier 193 on which the planetary gears 195 are        mounted is connected to the output shaft 190,    -   a hollow wheel 194 is connected to the driven shaft 137.

A switchable gear system 189 can, for example, be configured in such away that a first clutch is arranged between the sun wheel 192 and themotor housing 175 and a second clutch is arranged between the hollowwheel 194 and the sun wheel 192. By loosening the first clutch andtightening the second clutch the driven shaft 173 is connected directlyto the output shaft 190.

FIG. 38 shows the harmonic pin ring gear system in FIG. 31 with a gearsystem 189 that can be designed as one of the planetary gears describedabove, for example, or also as a rigid connection, and a derailleur gearsystem 196. The derailleur gear system comprises a first output pinion197 and a second output pinion 198 and a derailleur 199 to optionallyconnect a chain 200 to the first output pinion 197 or to the secondoutput pinion 198.

FIG. 39 shows a harmonic pin ring gear system 150′″ similar to the gearsystem in FIG. 26 in which the driven side is designed such that afurther change-speed gear system can be connected. In the embodiment inFIG. 39 a linear cam gear system 189 that is connected via a toothedbelt 217 to a drive gear of a vehicle that is not shown here is linkedto the driven shaft 37.

A mounting 132′ of the inner gear 105 and a mounting 138′ of the drivenshaft 137 that correspond to the mountings in the other embodiments arenot shown in FIG. 39.

A fixed wheel 206 of a first gear, a fixed wheel 207 of a second gearand a fixed wheel 208 of a third gear are pressed onto the driven shaft.An auxiliary shaft 210 is mounted on a ball bearing 209 in the motorhousing 175. An idler 210 of the first gear, an idler 212 of the secondgear and an idler 213 of the third gear are arranged on the auxiliaryshaft 210, wherein the idler 211 of the first gear engages in the fixedwheel 206 of the first gear, the idler 212 of the second gear engages inthe fixed wheel 207 of the second gear and the idler 213 of the thirdear engages in the fixed wheel 208 of the third gear. There is aclearance fit between the idlers 211, 212, 213 and the auxiliary shaft210, in other words the inner diameters of the idlers 211, 212, 213 aresomewhat larger than the diameter of the auxiliary shaft 210 so that theidlers 211, 212, 213 can slide on the auxiliary shaft 210.

From one end to the region in which the idlers 211, 212, 213 are locatedthe auxiliary shaft 210 is designed as a hollow shaft in which a linearcam shaft 214 is arranged such that it can be moved axially. A linearcam 215 is fixed to the linear cam shaft 214. The auxiliary shaft 210has a slit in axial direction in which the linear cam 215 is able tomove in axial direction. The linear cam 215 is dimensioned such that itconnects one of the idlers 211, 212, 213 in a friction fit to theauxiliary shaft 210 if the linear cam 215 is moved in an intermediatespace between the auxiliary shaft 210 and the idlers 211, 212, 213.

One end of the linear cam shaft 214 that protrudes past the auxiliaryshaft 210 is connected to a cable control that is not shown and that isconnected to an actuator and/or a hand lever. Here an additionalcomponent can be provided for the cable control that slides on thelinear cam shaft 214 such that a torque of the linear cam shaft 214 isnot transmitted to the cable control.

At one end of the auxiliary shaft 210 opposite the linear cam shaft 214an output pinion 216 is connected permanently to the auxiliary shaft210. A toothed belt 217 engages in the toothing of the output pinion216.

By moving the linear cam shaft 214 backwards and forwards, the idlers211, 212 and 213 can be connected either to the auxiliary shaft 210 bypressing the linear cam 215 into an intermediate space between therelevant idler 211, 212, 213 and the auxiliary shaft 210.

Instead of a linear cam gear system 189, it is also possible to connectother change-speed gear systems 189 such as a planetary gear, forexample, to the driven shaft 137 of the harmonic pin ring gear system.

Different aspects of the embodiments of this description can also bedescribed as in the following list. The various combinations of featuresdisclosed in the list are deemed independent subject-matters and canalso be combined with other features of this description.

-   1. Harmonic-pin ring gear system comprising:    -   at least one inner ring with external toothing and    -   at least one outer ring with internal toothing,    -   a pin ring with pins with a circular cross section,    -   a rotor with a transmitter for drawing the pins of the pin ring        into the teeth of the outer rings and into the teeth of the        inner ring,    -   wherein the inner ring, the rotor and the outer ring are        arranged concentrically in relation to one another, the        transmitter is arranged inside the pin ring and the transmitter        and the pin ring are arranged between the inner ring and the        outer ring, wherein the transmitter is deformed such that the        outer ring and the inner ring rotate in relation to one another,    -   wherein, moreover, the shape of the teeth of the outer ring and        the shape of the teeth of the inner ring are essentially        determined by the envelope of the moving pins and each of the        pins is in mesh with the internal toothing of the outer gear or        in mesh with the external toothing of the inner gear.-   2. Harmonic pin ring gear system according to list item 1, wherein    the apex of a pin central point of a pin as the pin moves from one    tooth base into an adjacent tooth base of toothing of the inner or    outer ring lies on a pitch circle of the opposite toothing.-   3. Harmonic pin ring gear system according to list item 2, wherein    the cross section of the tooth is shaped like a sector of a circle.-   4. Harmonic pin ring gear system according to one of the preceding    list items, wherein the tooth flanks run into the tooth base    perpendicular to the pitch circle of the toothing.-   5. Harmonic pin ring gear system according to list item 1, wherein    the pin trajectory of a pin centre point of a pin as the pin moves    from one tooth base into an adjacent tooth base is determined by a    section of an ellipse.-   6. Ring according to list item 1, wherein the pin trajectory of a    pin centre point of a pin as the pin moves from one tooth base into    an adjacent tooth base is determined by a section of a sine-overlaid    circular shape.-   7. Harmonic pin ring gear system according to list item 1, wherein    the pin trajectory of a pin centre point of a pin as the pin moves    from one tooth base into an adjacent tooth base is essentially    determined by a shape of the transmitter compressed along an angular    coordinate.-   8. Harmonic pin ring gear system according to one of the preceding    list items, wherein the root circle of the teeth of the inner gear    is essentially located twice the circumference of the pins from the    root circle of the teeth of the outer gear.-   9. Inner ring with external toothing for a harmonic pin ring gear    system comprising a pin ring with pins having a circular cross    section, a rotor with a transmitter for drawing the pins of the pin    ring into the teeth of the inner ring, wherein the inner ring and    the rotor are arranged concentrically in relation to one another and    the transmitter is arranged inside the pin ring, wherein the    transmitter deforms the pin ring such that the inner ring rotates    relative to an outer ring arranged concentrically to the inner ring,    -   wherein the inner ring        -   comprises tooth bases with a profile in the form of a            segment of a circle arranged a regular distances, and        -   teeth arranged between the tooth bases, wherein the shape of            the teeth is essentially determined by the envelope of the            moving pins.-   10. Inner ring according to list item 9, wherein the profile of the    tooth bases is semi-circular in shape.-   11. Inner ring according to list item 9 or list item 10, wherein the    tooth flanks run into the tooth base perpendicular to the pitch    circle of the toothing.-   12. Outer ring with external toothing for a harmonic pin ring gear    system comprising a pin ring with pins having a circular cross    section, a rotor with a transmitter for drawing the pins of the pin    ring into the teeth of the inner ring, wherein the outer ring and    the rotor are arranged concentrically in relation to one another and    the transmitter is arranged inside the pin ring, wherein the    transmitter deforms the pin ring such that the outer ring rotates    relative to an inner ring that is arranged concentrically to the    outer ring,    -   wherein the outer ring        -   comprises tooth bases with a profile in the form of a            segment of a circle arranged a regular distances, and        -   teeth arranged between the tooth bases, wherein the shape of            the teeth is essentially determined by the envelope of the            moving pins.-   13. Inner ring according to list item 12, wherein the profile of the    tooth bases are semi-circular in shape.-   14. Inner ring according to list item 12 or list item 13, wherein    the tooth flanks perpendicular to the pitch circle of the toothing    run into the tooth base.

Different aspects of the embodiments of this description can also bedescribed as in the following list. The various combinations of featuresdisclosed in the list are deemed independent subject-matters and canalso be combined with other features of this description.

-   1. Harmonic pin ring gear system comprising an input shaft and an    output shaft, wherein the harmonic pin ring gear system has the    following features:    -   an outer gear with internal toothing,    -   an inner gear with external toothing arranged concentrically to        the outer gear and in axial direction inside the outer gear, and    -   a drive means extending between the outer gear and the inner        gear, comprising a pin ring formed as one part in        circumferential direction and a multiplicity of pins that        protrude laterally in axial direction from the pin ring,    -   a rotary transmitter for lifting the drive means of the external        toothing of the inner gear and pressing the drive means into the        internal toothing of the outer gear,    -   wherein in a first region a radial force flow runs in a straight        direction from the transmitter via at least one pin to the        internal toothing of the outer gear and in a second region a        radial force flow runs in a straight direction from at least one        pin to the external toothing of the inner gear.-   2. Harmonic pin ring gear system according to list item 1, wherein a    radial force flow runs in a straight direction from the internal    toothing of the outer ring via at least one pin to the external    toothing of the inner gear.-   3. Harmonic pin ring gear system according to list item 1 or list    item 2, wherein the pin ring is located in axial direction on an    outer side of the outer gear.-   4. Harmonic pin ring gear system according to one of list items 1 to    3, wherein the drive means abuts the transmitter around its entire    circumference.-   5. Harmonic pin ring gear system according to list item 4, wherein    the transmitter comprises an oval-shaped cam disk and a flexible    thin-section roller bearing, wherein the flexible thin-section    roller bearing lies on the oval cam disk and the pins lie on an    outer ring of the flexible thin-section roller bearing.-   6. Harmonic pin ring gear system according to one of list items 1 to    3, wherein the drive means abuts the circumference of the    transmitter except in a first region about a first angular position    and in a second region about a second angular position, wherein the    first angular position is offset by 180 degrees in relation to the    second angular position.-   7. Harmonic pin ring gear system according to list item 6 comprising    a double eccentric cam with a first eccentric cam with a first axis    of rotation and a second eccentric cam with a second axis of    rotation, wherein the first angular position and the second angular    position are offset by 45 degrees in relation to a semi-major axis    connecting the first axis of rotation and the second axis of    rotation.-   8. Harmonic pin ring gear system according to one of the preceding    list items, wherein the transmitter is connected to the input shaft    and the output shaft is connected to the inner gear or to the outer    gear.-   9. Harmonic pin ring gear system according to one of list items 1 to    7, wherein the transmitter is connected to the output shaft and the    input shaft is connected to the inner gear or to the outer gear.-   10. Harmonic pin ring gear system according to one of the preceding    list items, wherein the pin ring comprises channels arranged in    axial direction for receiving the pins that arranged on an inside of    the pin ring.-   11. Harmonic pin ring gear system according to one of the preceding    list items comprising a second pin ring arranged in radial direction    in relation to the inner ring, whereby an end region of the pins is    arranged between the second pin ring and the inner ring.-   12. Harmonic pin ring gear system according to one of the preceding    list items comprising a middle pin ring, wherein a middle region of    the pins abuts the middle pin ring and the outer gear comprises a    channel in which the middle pin ring runs.-   13. Harmonic pin ring gear system according to one of the preceding    list items, wherein the inner gear comprises an inner gear holder    fixed to the inner gear and comprises an inner gear roller bearing    supported radially inwards on a gear housing, wherein the inner gear    and the inner gear holder encompass an outer ring of the inner gear    roller bearing.-   14. Harmonic pin ring gear system according to one of the preceding    list items, wherein the output shaft is designed as a hollow driven    shaft and comprises a freewheel, wherein the freewheel is arranged    between the driven shaft and an inner region of the inner gear.-   15. Harmonic pin ring gear system according to one of the preceding    list items comprising a crankshaft and a crankshaft freewheel,    wherein the crankshaft is arranged concentrically to the hollow    driven shaft inside the hollow driven shaft and the crankshaft    freewheel is arranged between the crankshaft and the hollow driven    shaft.-   16. Harmonic pin ring gear system according to one of the preceding    list items comprising a first thrust washer and a second thrust    washer, wherein the first thrust washer is arranged adjacent to a    first axial lateral face of the pins and the second thrust washer is    arranged adjacent to an opposite second axial lateral face of the    pins.-   17. Harmonic pin ring drive of the gear unit comprising a harmonic    pin ring gear system according to one of the preceding list items    and a motor unit, wherein a rotor shaft of a motor of the motor unit    is connected mechanically to the cam disk of the gear unit.-   18. Harmonic pin ring drive according to claim 17, wherein the motor    is designed as an internal rotor motor.-   19. Motor vehicle comprising a harmonic pin ring drive according to    list item 16 or list item 17, wherein a drive gear of the motor    vehicle is connected to the output shaft of the harmonic pin ring    drive.-   20. Pin ring arrangement comprising a multiplicity of pins, a pin    ring for holding the pins and a transmitter for exerting a radially    outwardly directed force onto the pins, wherein the transmitter is    arranged inside the pin ring and the pins lie at least predominantly    on a outer circumference of the transmitter.-   21. Pin ring arrangement according to list item 20, wherein the    transmitter comprises an eccentric cam arranged eccentrically to an    axis of rotation of the transmitter.-   22. Pin ring arrangement according to list item 21, wherein the    transmitter comprises a second eccentric cam arranged eccentrically    to an axis of rotation of the transmitter.-   23. Pin ring arrangement according to list item 20, wherein the    transmitter comprises an oval cam disk and a thin-section ball    bearing that lies on the oval cam disk, wherein the pins lie on an    outer ring of the thin-section ball bearing.

Different aspects of the embodiments of this description can also bedescribed as in the following list. The various combinations of featuresdisclosed in the list are deemed independent subject-matters and canalso be combined with other features of this description.

-   1. Harmonic pin ring gear system comprising an input shaft and an    output shaft, wherein said harmonic pin ring gear system has the    following features:    -   two outer gears, each with internal toothing,    -   a single inner gear with external toothing arranged        concentrically to a first outer gear and inside said first outer        gear in axial direction, and    -   a drive means extending between the two outer gears and the        inner gear comprising a pin ring formed as one part in        circumferential direction and a multiplicity of pins that        protrude laterally in axial direction from the pin ring,    -   a rotary transmitter for lifting the drive means off the        external toothing of the inner gear and pressing the drive means        into the internal toothing of the outer gear.-   2. Harmonic pin ring gear system according to claim 1, characterised    in that    -   in a first axial region a radial force flow runs in a straight        direction from the transmitter via at least one pin to the        internal toothing of the outer gear, wherein in a second axial        region a radial force flow runs in a straight direction from at        least one pin to the external toothing of the inner gear.-   3. Harmonic pin ring gear system according to claim 1 or claim 2,    -   wherein a radial force flow runs in a straight direction from        the internal toothing of the outer ring via at least one pin to        the external toothing of the inner gear.-   4. Harmonic pin ring gear system according to one of claims 1 to 3,    wherein the pin ring is located on one outer side of the outer gear    in axial direction.-   5. Harmonic pin ring gear system according to one of claims 1 to 4,    wherein the drive means abuts the transmitter around its entire    circumference.-   6. Harmonic pin ring gear system according to claim 5, wherein the    transmitter comprises an oval-shaped cam disk and a flexible    thin-section roller bearing, wherein the flexible thin-section    roller bearing lies on the oval cam disk and the pins lie on an    outer ring of the flexible thin-section roller bearing.-   7. Harmonic pin ring gear system according to one of claims 1 to 4,    wherein the drive means abuts the circumference of the transmitter    except in a first region about a first angular position and in a    second region about a second angular position, wherein the first    angular position is offset by 180 degrees in relation to the second    angular position.-   8. Harmonic pin ring gear system according to claim 7 comprising a    double eccentric cam with a first eccentric cam with a first axis of    rotation and a second eccentric cam with a second axis of rotation,    wherein the first angular position and the second angular position    are each offset by 45 degrees in relation to a semi-major axis that    connects the first axis of rotation to the second axis of rotation.-   9. Harmonic pin ring gear system according to one of the preceding    claims, wherein the transmitter is connected to the input shaft and    the output shaft is connected to the inner gear or to one of the two    outer gears.-   10. Harmonic pin ring gear system according to one of claims 1 to 8,    wherein the transmitter is connected to the output shaft and the    input shaft is connected to the inner gear or to the outer gear.-   11. Harmonic pin ring gear system according to one of the preceding    claims, wherein the pin ring comprises open channels arranged in    axial direction to receive the pins that are arranged on an inner    side of the pin ring.-   12. Harmonic pin ring gear system according to one of the preceding    claims comprising a second pin ring arranged in radial direction in    relation to the inner ring, wherein a end region of the pin is    arranged between the second pin ring and the inner ring.-   13. Harmonic pin ring gear system according to one of the preceding    claims comprising a middle pin ring, wherein a middle region of the    pin abuts the middle pin ring and the outer gear has a channel in    which the middle pin ring runs.-   14. Harmonic pin ring gear system according to one of the preceding    claims, wherein the inner gear comprises an inner gear holder that    is fixed to the inner gear and an inner gear roller bearing    supported radially inwardly by a gear housing, wherein the inner    gear and the inner gear holder encompass an outer ring of the inner    gear roller bearing.-   15. Harmonic pin ring gear system according to one of the preceding    claims, wherein the output is designed as a hollow driven shaft and    has a freewheel, wherein the freewheel is arranged between the    hollow driven shaft and an inner region of the inner gear.-   16. Harmonic pin ring gear system according to one of the preceding    claims comprising a crankshaft and a crankshaft freewheel, wherein    the crankshaft is arranged concentrically to the hollow driven shaft    inside the hollow driven shaft and the crankshaft freewheel is    arranged between the crankshaft and the hollow driven shaft.-   17. Harmonic pin ring gear system according to one of the preceding    claims comprising a first washer and a second thrust washer, wherein    the first thrust washer is arranged adjacent to a first axial    lateral face of the pins and the second thrust washer is arranged    adjacent to an opposite second axial lateral face of the pins.-   18. Harmonic pin ring gear system according to one of the preceding    claims, wherein the outer gears are held in their positions relative    to the central axis of the gear system by a frictional connection    and have radial play relative to this position when loose.-   19. Drive shaft for transmitter is mounted on one side in the inner    gear which is in turn mounted in the housing.-   20. Harmonic pin ring drive comprising a gear unit with a harmonic    pin ring gear system according to one of the preceding claims and a    motor unit, wherein a rotor shaft of a motor of the motor unit is    connected mechanically to the cam disk of the gear unit.-   21. Harmonic pin ring drive according to claim 20, wherein the motor    is designed as an internal rotor motor.-   22. Harmonic pin ring drive according to claim 20 or claim 21,    wherein a driven shaft arranged inside the input shaft is mounted on    two bearings, wherein the motor is provided between the two bearings    of the drive shaft.-   23. Harmonic pin ring drive according to claim 22, wherein the    driven shaft is designed in two parts, wherein a support shaft is    fixed on the driven shaft.-   24. Harmonic pin ring drive according to one of claims 20 to 23    comprising a pedal bearing shaft arranged in the driven shaft and a    torque sensor in the region between the driven shaft and the pedal    bearing shaft, wherein the driven shaft is designed such that the    torque sensor is shielded from electromagnetic radiation of the    stator.-   25. Motor vehicle comprising a harmonic pin ring drive according to    one of claims 20 to 25, wherein a drive gear of the motor vehicle is    connected to the output shaft of the harmonic pin ring drive.-   26. Pin ring arrangement comprising a multiplicity of pins, a pin    ring for holding the pins and a transmitter for exerting a radial,    outwardly directed force onto the pins, wherein the transmitter is    arranged inside the pin ring and the pins lie at least predominantly    on a outer circumference of the transmitter.-   27. Pin ring arrangement according to claim 26, wherein the    transmitter comprises an eccentric cam arranged eccentrically to an    axis of rotation of the transmitter.-   28. Pin ring arrangement according to claim 27, wherein the    transmitter comprises a second eccentric cam arranged eccentrically    to an axis of rotation of the transmitter.-   29. Pin ring arrangement according to claim 26, wherein the    transmitter comprises an oval cam disk and a thin-section ball    bearing that lies on the oval cam disk, wherein the pins lie on an    outer ring of the thin-section ball bearing.

1. A harmonic ring gear system comprising: at least one inner gear withexternal toothing, the at least one inner gear defining an axis ofrotation; at least one outer gear with internal toothing arrangedconcentrically to the at least one inner gear about the axis ofrotation, the internal toothing spaced apart from the external toothing;a pin ring positioned between the at least one inner gear and the atleast one outer gear, the pin ring comprising a multiplicity of pins;and a rotary transmitter configured to lift a portion of the pins of themultiplicity of pins off the external toothing and press the portion ofthe pins into the internal toothing.
 2. The harmonic ring gear system ofclaim 1, wherein a first pin of the multiplicity of pins defines acircular cross section.
 3. The harmonic ring gear system of claim 2,wherein the pin ring defines grooves, and wherein the grooves receivethe multiplicity of pins.
 4. The harmonic ring gear system of claim 1,wherein the pin ring is a first pin ring, and wherein the harmonic ringgear system further comprises a second pin ring.
 5. The harmonic ringgear system of claim 4, wherein the outer gear is positioned the firstpin ring and the second pin ring.
 6. The harmonic ring gear system ofclaim 1, wherein: the multiplicity of pins comprises a number of pins;the external toothing comprises a number of teeth; and the number ofpins is two more than the number of teeth.
 7. The harmonic ring gearsystem of claim 1, wherein: the multiplicity of pins comprises a numberof pins; the internal toothing comprises a number of teeth; and thenumber of pins is two less than the number of teeth.
 8. The harmonicring gear system of claim 1, wherein each tooth of the external toothingof the at least one inner gear defines a semi-circular tooth base. 9.The harmonic ring gear system of claim 1, wherein a first pin of themultiplicity of pins engages an apex of a tooth of the internalteething, wherein each tooth of the external teething defines a toothbase, and wherein the first pin is positioned between two tooth bases oftwo adjacent teeth of the external teething.
 10. The harmonic ring gearsystem of claim 1, further comprising a flexible ball bearing, themultiplicity of pins positioned against the flexible ball bearing. 11.The harmonic ring gear system of claim 10, wherein the flexible ballbearing is arranged on the rotary transmitter.
 12. The harmonic ringgear system of claim 10, wherein the flexible ball bearing comprises: aflexible inner ring; a flexible outer ring positioned around theflexible inner ring; and a multiplicity of balls positioned between theflexible inner ring and the flexible outer ring.
 13. A drive meanscomprising: a pin ring formed as one part in a circumferentialdirection, the pin ring extending around an axis of rotation, the pinring being flexible; and a multiplicity of pins protruding laterallyfrom two sides of the pin ring in an axial direction relative to theaxis of rotation; and wherein an inward-facing surface of the drivemeans is configured to engage external toothing of an inner gear, and anoutward-facing surface of the drive means is configured to engageinternal toothing of an outer gear.
 14. The drive means of claim 13,wherein each tooth of the external toothing of the inner gear defines asemi-circular tooth base.
 15. The drive means of claim 13, wherein afirst pin of the multiplicity of pins defines a circular cross section.16. The drive means of claim 13, wherein each pin of the multiplicity ofpins defines a circular cross section.
 17. The drive means of claim 13,wherein the pin ring defines grooves, and wherein the grooves receivethe multiplicity of pins.
 18. The drive means of claim 17, wherein thegrooves each define a semi-circular cross section.
 19. The drive meansof claim 13, wherein the multiplicity of pins are arranged equidistantlyon the pin ring.
 20. The drive means of claim 13, further comprising aflexible thin-section roller bearing, the multiplicity of pins lying onan outer ring of the flexible thin-section roller bearing.